DASH7 (ISO 18000-7): An ultra-low power wireless data technology famous for its performance and reliability by NATO militaries and commercial customers.  It’s range of up to 1,000 meters, long battery life and ability to penetrate water and concrete make it preferable to the older ZigBee technology.

DATA: The stuff that’s either manually entered or imported into a computer that is then manipulated by a computer program.  Data can be items of information, such as text, numbers, statistics or other information.

DATABASE: A structured collection of “records,” each containing specific “fields,” which are stored in a computer system for organization and retrieval.  Think of a database as a collection of recipes, each on a 3 x 5 card (the “record”) with the same type of information in the same place on each card (i.e. name, category (appetizer, main course, dessert), ingredients, cooking instructions, serving instructions, source; the “fields”).  You can search through all of the records according to the fields for each record (e.g. desserts, chocolate, from Aunt Margaret).  Databases can be either “flat” (consisting of one large table), “relational” (consisting of several interconnected tables, representing complex data relationships) or hierarchical (a record structure linking records like a “family tree,” such that access to each record type starts at the top of the hierarchy and moves downward).

DATA-CENTRIC: A buzz word for computers, networks or programs which focus on collecting, distributing and analyzing both structured and unstructured data.

DATA HOTELS: See, Server Farms.

DAUGHTER BOARD: A printed circuit board (other than a modem, sound or video board - see riser board) that plugs into the number one slot on a mother (main) board, usually carrying the main processor and cache memory.

DBA: Database Administrator.

DBMS:  Database Management System.  Generally, a database is exactly what it sounds like; a collection of data, which is stored in records containing fields of information (much like a recipe card in a storage box).  It needs a program that is a DBMS that enables storage, modification and extraction of pertinent data from the database.  Requests for information from a database are generally made in the form of a query.  The set of rules for constructing queries is known as a query language.  Different DBMSs support different query languages, although SQL is most often used.  These languages are often called 4GLs, standing for Fourth Generation Languages.  Depending on the way that the data is organized within the program, databases can be relational, network, flat and hierarchical. (See, for example, RDBMS and DATABASE.)

DCIM:  Stands for Digital Camera IMages. This is a default folder for digital camera (even smartphone camera) images.  It is intended to keep images organized.  For example, if you insert a memory card into a digital camera, the camera immediately looks for the DCIM file to store images and, if none exists yet, it will create one. Same for many scanning and photo editing software programs, they look for the DCIM folder by default.

DCOM: Distributed Component Object Model (formerly Network OLE [Object Linking & Embedding]) is a Microsoft technology for defining the remote procedure calls that allow distributed objects to be run remotely over a network.  DCOM is Microsoft’s counterpart to CORBA (Common Object Request Broker Architecture) from other vendors.  This is hard to describe in English, but basically this is the software that allows the coordination of various software modules that are designed to work together but reside in multiple computer systems, so that a program in one machine sends a message to an object in a remote machine to perform some processing, and then the results are sent back to the calling machine.

DEDUPLICATION:  A/K/A “Dedupe”.  The process of removing identical or similar records which appear in a database, such as a mailing list.

DELL:  One of the largest U.S. computer manufacturers and information technology corporations.  Named after its founder, Michael Dell, who started the company back in 1984 while a student at the University of Texas.

DEFCON:  A conference, usually held in Las Vegas each year at the end of July or beginning of August, started in 1992 by the Dark Tangent, which is the world’s longest and largest underground hacking conference.  The founder of this conference, Jeff Moss, also started the Black Hat convention, much more expensive to attend.  Both are the most famous computer security conferences in the world, where hackers meet to discuss ways to protect criminals from penetrating businesses, governments, power grids, air traffic controls, etc.

DEFAULT: While, in some circles, the term default connotes bad things (e.g. “You’re in default on your mortgage payments” - meaning failure, inaction or neglect on your part), in computers it’s a completely different and benign thing. It refers to a predesigned setting that is used by a computer or program when nothing more specific is supplied.  For example, the default printer is the one that the computer assumes is the standard printer for programs on that computer.  The default settings for Windows are those standard settings created upon installation, unless specifically modified. Often synonomous with the term “factory settings”. When modifications to the default are removed, the settings immediately revert back to the default or factory settings.

DEFRAG:  Means defragmentation. Regardless of how Windows portrays your folders and files (My Computer, Windows Explorer), your computer files are actually always “fragmented” (exploded into small segments throughout the disk) when stored on the hard drive.  Consequently, the storage “blocks” on the drive must be periodically rearranged by defragmentation so that they are compressed into fewer, more easily accessible, fragments which are at least more contiguous to each other.   The files are sent to the outside of the disk, based on their size and frequency of use, beginning with the Master Boot Sector, leaving more space on the interior of the disk.  The computer can then store more data on the drive more efficiently, which reduces access time to display files. [Don’t use on SSDs, though - they can shorten their life.]

DEMARC:  Sometimes called MPOE (Minimum Point Of Entry).  In telephony, the demarcation point is the point at which the telephone company network (Public Switched Telephone Network, i.e. PSTN) ends and connects to the cabling at the customer’s premises.  This is defined by FCC Rules 47 CFR Part 68.  The actual demarc point is the network interface device (“NID”)/ channel service unit (“CSU”) connection:  The NID is the telco’s property; the CSU is the customer’s.  Usually the residential NID is at a grey plastic waterproof junction box on the outside of the home which contains a lightning arrestor, fuse and test circuitry for the telco’s remote testing of the connection.  Also, there is a test jack which is usually connected to a loop of wire, to be used to isolate and troubleshoot faults in the premises wiring.   Commercially the NID is usually a 66 or 110 Block, the left side of which is the incoming cable from the telco, the right side of which is customer premises wiring. See, 66 Block.

DEP:  A Windows technology security feature in Windows Vista and Internet Explorer 8 which is intended to prohibit hackers from writing code into pagefiles and swapfiles by inserting a special bit into the disk version of an address, making it non-executable.  If DEP senses a problem, it may prevent you from opening a specific program (you would then have to deactivate DEP).

DEVICE:  As used in this Glossary, an item of hardware (such as a computer, printer, TV, phone or the like), or sometimes a subassembly of that hardware (modem, card or board), as opposed to the software or instructions that control that particular hardware.

DHCP: Short for “Dynamic Host Configuration Protocol”. Your computer has devices like broadband modems that may have a different IP address every time you connect to the Internet network, even more often.  DHCP keeps track of these changes and automatically keeps you connected to the Internet even if the IP address changes.  DHCP servers are assigned a range of IP addresses and assigns an unused address from this range each time a host signs on.

DIGERATI:  The digital version of literati, a reference to a group of people expected to be knowledgeable about all thing digital.

DIGITAL: This describes electronic technology that generates, stores and processes data in terms of two states: positive and non-positive.  Positive is represented by the number 1, non-positive by 0.  Thus, digital data is expressed by a string of O’s and 1’s.  Each of these digits is a bit.  For more discussion, see Bits and Bytes, above.  The predecessor to digital technology was analog.

DIGITAL BOOK:  See, e-book.

DIGITAL CERTIFICATE: A sort of electronic “credit card” that establishes your credentials when transacting business on the Web.  It is issued by a Certification Authority and contains your name, a serial number, expiration date and a copy of your public key (see PKI), so that the recipient can verity that your certificate is real. 

DIGITAL SIGNATURE: An electronic signature that can be used to authenticate the identity of the sender of a message or signer of a document.  Digital signatures are unique, can be time-stamped and cannot be imitated.  You need PKI to do this.

DIGITAL WALLET:  See, Wallet.

DIN CONNECTOR: DIN is short for Deutsches Institut fur Normung dV, the standards setting organization for Germany.  In many of the earlier PCs, DIN connectors were used for cable attachments.  See, e.g. photos of the keyboard DIN connector HERE.  DIN connectors also defined Centronics and RS-232 (DB-25) connectors. See the same link for photos.

DIRECT  ACCESS: A Windows 7 technology that lets employees remotely access corporate networks without using a VPN. Instead of establishing a connection and logging in to access corporate resources, things like file shares, intranet websites and network applications are made available to authorized DirectAccess clients.  However, establishing and maintaining DirectAccess on the administrative side is fairly complex, requiring such procedures as tunneling and security certificates, making this feature more suitable for larger organizations.

DIRECTORY:  A part of the file system which contains files and is sometimes referred to as a folder.  The computer operating system  organizes these folders into a hierarchical structure often referred to as an “inverted tree.”  The topmost directory in any file is known as the “root” directory (in DOS and Windows, the root directory is begins with a backslash (“\”)).  The directory below another directory is called the “subdirectory.”  And a directory above another directory is known as the “parent directory.”  In Unix and Linux, the directory you log in to is known as the home directory.  The directory you are currently working in is the working directory.  To directly access a file in a directory, you must use an operating system command.  Indirectly, it can be accessed through the appropriate program.  If you are using a command line, you must specify the entire path to the file, listing the names of all of the directories above the file with a backslash in between each.  [e.g.:  “C:\Users\Joe\Program Files\Office 12\Word\resume.wpd”]  Path names can be either absolute (the full path from the root directory, e.g. “/home/joe/work”) or relative (the path from your working directory, e.g. “joe/work”). 

DISCO:  Not a throwback to the ‘80s, a .disco file is a Web Service Directory file which opened by an SQL database app and InfoPath (an app included in the premium versions of MS Office.

DISINTERMEDIATION: Actually more of an economic term, it means to “remove the middle man.”  For example, selling products on the Internet directly to consumers may eliminate brick-and-mortar storefronts; selling downloadable applications for cell phones may eliminate carrier distinctions.

D2C: Stands for “Disk to Cloud” which refers to storing data from a computer or network to the public cloud for security.  Similarly, D2D2C refers to “Disk to Disk to Cloud” which is storage to a private cloud, which allows more corporate control and hence more security for sensitive data.

DISK:  See, hard drive.

DISPLAY FORMAT:  Refers to the overall width vs. height format (also sometimes called the “aspect ratio”) of a video display.  While it started as 4:3, presently standard formats are usually either 3:2 or 16:9.

DISTRIBUTED DATA: A database where the data is not all stored on the same storage device or CPU, but is instead stored on multiple computers either in the same physical location or even over a network of interconnected computers in various physical locations.  Opposite: Centralized, all on one computer.

DISTRIBUTED MODEL/DISTRIBUTED NETWORK MODEL - “DISTRUBUTED COMPUTING”: A computer network in which the individual server computers act relatively independently, although they may still be connected to a central server, so that individual users experience a uniform experience when it comes to performance and applications, even though they may not be on their individual computer.  See also, cluster, parallel, grid and cloud computing.  Similarly, as relates to a business organization, one in which individual branches act relatively independent of each other and the head office.  Relatively independent means that they may all share inventory, communicate with each other, and leave the accounting , billing and purchasing functions to the head office. 

DISTRO:  Short for “Distribution.”  This term is mainly used in Linux, and it refers to a version of Linux made by a specific distributor (e.g. Red Hat, Ubantu, etc.).  In Linux, all distributions use the Linux kernel, but everything else is different for each distribution, making each unique to a limited extent.  So a Distro is a compilation of software and then some additions which make the software unique.  Somewhat like the way Windows software can be slightly different for business, home, pro, etc.  A comprehensive list of distros and their attributes can be found at Wikipedia, click HERE for the link.

DLL: Dynamic Link Library file.  This is a very important file that is created in Windows upon the installation of every program, which “links” that program to a “library” of instructions about the operating system.  The file itself contains a library of procedures for that program (or sometimes a group of programs), essentially linking the execute file for that program with the rest of Windows, such as the printers or monitors, through mini-programs that can be called upon if and when needed. If the dll file is  missing or damaged, you get a “dll error” from Windows and your program will simply not open.

DLL HELL: A term referring to a situation where different versions of the same program can require different DLLs to start them up.  Since Windows Vista, a file named WinSxS has remedied the problem where those updated DLLs often broke programs that still required the older ones.

DLNA: Digital Living Network Alliance.  An organization established in September, 2005 that certifies wired and wireless digital products such as personal computers, consumer electronics and mobile devices toward the end of enabling a seamless environment for sharing those devices and their content.  The DLNA Certified logo ensures that a device has been tested and proven to be interoperable among various other devices that have been designed according to the DLNA interoperability guidelines.

DLP: Data Loss Protection. Used mostly in larger organizations, DLP involves scanning outgoing data such as web traffic (including web mail), IM, FTP and any other mode that sends electronic data out of an organization to prevent leakage of important corporate data or intrusion through unauthorized ports.

DMA: Direct Memory Access. This is a capability provided by some computer boards that allows data to be sent directly from an attached device (such as a  drive) to the memory on the computer’s motherboard, freeing the processor from involvement, thus speeding up the computer’s operation.  The alternative to DMA is PIO (“Programmed Input/Output”) in which all data transmitted between the devices goes through the processor.  A newer protocol is Ultra DMA, now on many SATA/IDE hard drives, which provide a “burst” data transfer up to 33  megabytes per second

DMI: Short for Desktop Management Interface, an API that allows software to collect information about a computer environment (hardware and software components).  This automates system management and is particularly beneficial in enterprise environments where many computers are being managed.

DNS: Domain Name System (or, sometimes, Service or Server).  As discussed in URL, the Internet is based on numeric IP addresses, which are usually also English domain names.  DNS is the internet service that translates domain names into IP addresses, e.e. from “computercoach.com” to “162.122.143.565” and vice versa.

DNS FILTERING: A type of web filtering for those subscribers who don’t have ISPs which don’t offer web filtering.  Instead, you can block suspect sites by switching your DNS server settings to go through a specific third-party DNS provider which can provide such security services (e.g. OpenDNS).

DNS REBINDING:  An Internet intrusion by which hackers use extra IP addresses for legitimate web sites in order to obtain access to routers and then computers which do not have adequate password and firmware protection.  It is not browser specific, and only applies to some routers.  See Security.

DOCK: On Apple OS X computers and some PCs (HPs and the like), it is a user-modifiable row of icons that appears on the desktop with program shortcuts for easy selection.  Not to be confused with a docking station, which is a piece of hardware into which a laptop or notebook computer is placed, so that it more closely resembles a desktop computer, containing ports for printers, serial devices and the like.  Some docking stations are known as port replicators because they expand the number of ports and/or drives that the notebook can use but, unlike a docking station, they do not include an expansion slot. Some docking stations like Samsung’s Central Station are completely wireless.

DOCSIS:  Cable modems use Data Over Cable Service Interface Specification  technology, including authentication and packet filtering, and providing built-in hardware firewalls, so that their networks are secure.

For a list of the country-code and other top level domains, click HERE.

DOMAIN: A domain name is an easy-to-remember shortcut or handle for a numeric internet address. A Top Level Domain (“TLD”) would be either Generic or Country Code.  For example:  The fictitious internet address http://technet.computercoach.com would mean that the entire name is the top-level domain, computercoach.com is the second-level domain, and technet is a subdomain name.  Domain names, as regulated by Icann, have been limited to 37 characters (26 Latin characters, 10 digits and a hyphen).  Beginning in 2010, however, Icann will begin permitting domain names in non-Latin alphabets (e.g. Farsi, Hebrew, Chinese) in an effort to “internationalize” the Internet. And, in June 2011, ICANN approved an increase in the number of generic top level domains (“gTLDs”) from the current 22 (.net, .com and .org most common), adding new ones such as .cars, .sports, .museums, and the like.

DONGLE:  The more generic definition of dongle is a any very short cable used to connect hardware to a computer which cannot otherwise be connected, for example a cable to connect a PC ethernet card to a laptop USB port which might otherwise be too small to insert directly into the PC.  More specifically, a dongle is a “security key” that is usually a plug or connector which is situated between the keyboard, serial or printer port and the hardware it seeks to secure.

DOS and DDOS:  Denial of Service and Distributed Denial of Service attacks. A DOS is an attack by a single computer (IP address) on a target web domain computer by inundating it with a tremendous number of packets, thereby overwhelming it and effectively shutting it down (i.e. “denying service”), making it too busy to respond to legitimate web traffic.  A DDOS is a geometrically more serious attack, because it is caused by a multitude of compromised computers (a “botnet” of hundreds, thousands or more unsecured and probably unaware “zombie” computers) which flood the targeted system in waves from many different IP addresses, not only continually incapacitating the target but also making it virtually impossible to filter out the “garbage” IP connection requests.  Of course, both the botnet and the targeted system are victims of this type of Trojan, which cannot be resolved as can a DOS, by finding and blocking the single IP address of the attacker.  Don’t confuse this with the DOS operating system (See below),  See also, SMURF ATTACK.

DOS:  See, Operating System. Disk Operating System, allegedly purchased by Bill Gates from a Seattle hacker for $50,000, later pioneered by Microsoft, which became the basis for most PCs today. Developed by Microsoft in 1980 for IBM (PC-DOS), Gates retained the right to market DOS separately from the IBM PC, as MS-DOS, the precursor to MS Windows.  For a listing of common DOS commands, click HERE.  For more history and explanation, click HERE.

DOT COM:  Anything relating to a business conducted on the Internet.  Derived from “.com”, which is attached to most website addresses for commercial websites (e.g. travelocity.com, ebay.com).

DOT.NET (.NET):  This is a “platform” (i.e. a hardware or software “framework” such as a computer’s operating system or programming languages) from Microsoft which supports what are known as “Web Services,’ which means the ability to use the Web rather than your own computer for various services.  It’s gone through lots of name changes.  .Net is supposed to make an entire range of computing devices work together and to have user information automatically updated and synchronized on all of them.  For example, Passport (Microsoft’s fill in the form only once) identity verification service, is part of .net.  Despite at least four versions, .Net isn’t yet nearly complete, which makes it that much harder to define.  In theory, applications written using .NET should interpret with those written in rival architectures, such as Java J2EE; however, this should not be confused with portability - .NET applications will only run on Microsoft platforms (XP, Windows Server, etc.) In actuality, .Net has caused so many problems that we usually remove it entirely, as it seems to cause other problems with the operating system.

DOT PITCH :  The distance, diagonally, between two phosphors of the same color on a CRT video display.  On LCD screens, however, the resolution of a monitor is simply the number of pixels contained in its matrix and is therefore pre-defined (e.g. a 17” LCD monitor is 1280 x 1024).  Some manufacturers, however, have been known to improperly define dot pitch as the horizontal distance between phosphors, in an effort to increase their specifications.  DP times the viewable screen area equals the maximum screen resolution.  Generally, the lower the DP, the sharper the screen image. [Image Credit: bit-tech]

DOUBLE ENTRY ACCOUNTING SYSTEM: I put this one in only because we receive so many questions about Quicken and MS Money.  Programs like Quicken are single entry accounting systems.  They are for so-called “cash basis” taxpayers, and they record, in a register, expenditures and income at the time that the payment for the expense is made and the time that the income is received.  This might be fine for an individual, but not for a business.  Business use double entry accounting systems because they have to account for “payables” and “receivables”.  They show expenses when they receive the statement and income when it is billed.  Then, when the income check is actually received, the account payable is adjusted by the amount received, and when the bill is actually paid, the payable account is reduced by the amount paid.  Business, therefore, use a double-entry type program like QuickBooks.

DOWNLOAD: A verb, meaning to transfer data and files from one computer (usually a larger one) to another (usually smaller one), often over the Internet.  For example, one downloads MP3 music files from iTunes onto their computer or iPod.  The term also refers to the transfer from a computer to a peripheral device, like an iPhone.  See also, Upload.

DOWNSTREAM: Applies to the speed of an internet connection when downloading a file to your computer from another computer over your internet connection.  These speeds are typically higher than upstream transfers over the same network.

DP:  See Dot Pitch, above; also sometimes called “pixel pitch”.  The smaller this number, which is expressed as .xx, the crisper the image.  The number itself represents the distance in millimeters between dots on a color monitor; .28 is normal for CRT monitors, LCD anywhere from .16 to .29.

DPI:  Deep Packet Inspection.  This is a method that makes it possible for an ISP to identify, classify, reroute or block packets of specific data or code sent over the Internet.  This, as opposed to conventional packet filtering, which only examines the packet headers.  It is also a method used by some ISPs to track the web usage of its customers, usually to direct advertising to them.

DRIVE:  See “Hard Drive”.

DROID:  Short for Android, Google’s smartphone operating system. The Droid character is shown on the left.  Not to be confused with the Noid (at right), the 1980s character which attempted to ruin Dominos pizzas.

DRM:  “Digital Rights Management”.  A technology created by publishers of music and video to control the unauthorized duplication and distribution of their work product.

DROPBOX AND BOX:  See Cloud.  Free personal cloud storage.

DRP:  Disaster Recovery Plan.  Just like what it says, this is a plan to get your computers back up and running after a natural or man-made disaster damages or destroys your computer system.  Click for DRP considerations.

Dr. WATSON: Of course, we could mean the U.S. telephone engineer (Thomas A., 1854-1934) who assisted Alexander Graham Bell in his experiments.  Or, possibly, the British doctor (John H.) who assisted the fictitious detective Sherlock Holmes. Or even the door-to-door salesman Thomas Watson who founded the company that became IBM.  However, we refer to a program error debugger (Drwtsn32.exe) incorporated into Windows (starting with the XP version) which creates a text file (Drwtsn32.log) which can be used by technical support to diagnose a program error, named we assume for its detective-like abilities like Holmes’ sidekick.  Don’t confuse this with plain old Watson, the IBM IA supercomputer.

DSL: Digital Subscriber Line, over which computers can connect to the Internet at high speed.  Click HERE for more.

DTMF: (Stands for “Dual Tone Multi-Frequency). Tone (as opposed to pulse) phone dialing.

DUAL BAND: Refers to routers which operate at both the 2.4Ghz and 5Ghz band. 

DUNBAR NUMBER: A number postulated in the 1990s by British professor of evolutionary anthropology Robin Dunbar (popularized by Malcolm Gladwell’s book, published in 2000,  “The Tipping Point” about the dynamics of social groups), to be the the maximum number of people (generally believed to be 150) with whom one person can have strong relationships.  It is primarily based on the human brain’s neocortex size as well as studies of villages and settlements, and cannot ever be exceeded as the brain cannot be expanded.  Web developers find this number useful in determining how social networking and gaming sites can function with so many members; also the number has been applied to determine the maximum number of people in an office or in educational classes. 

DUPLEX:  A term meaning that both ends of a communication (telephone, computer, etc.) can simultaneously send and receive.  Ordinary telephone calls, for example, are full duplex.  Parties can both talk and listen at the same time.  Half-duplex, on the other hand, is still bi-directional but signals can only flow in one direction at a time.  Speakerphones are usually half-duplex - if you are speaking, you can’t hear anyone else interrupt unless you pause to let them speak.  Simplex is not duplex at all, but is a term for a communication signal which flows in only one direction, never back the other way. 

DVD-RAM:  Stands for DVD-Random Access Memory.  DVD-RAM disks can be recorded and erased repeatedly, but only on devices which support this technology.

DVD REGION CODE:  Also Country Code, or Code Lock.  Primarily as the result of pressure from the movie industry, to preserve recording agreements and distribution rights, pre-recorded DVDs are given codes for each country that they are released in, requiring that they be played on a recorder matching the same region.  This is done because movies are released in different countries on different dates.  There are 8 codes, Code No. 1 for the U.S. and Canada, and the last two codes (7 & 8) for cruise ships and airlines.  Code 0 DVDs are uncoded and can be played anywhere.

DVI: Digital Video Interface.  This is a specification created by the Digital Display Working Group (DDWG) to accommodate both analog and digital monitors with a single connector.  There are three different DVI connector pin configurations:  DVI-A (analog only). DVI-D (digital only) and DVI-I (integrated, i.e. for both types of signals).  DVI connectors have lots of little pins, as opposed to standard VGA 41 pin connectors.  For photos, see connectors.

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