RAID:  Stands for “Redundant Array of Independent Disks”.  This involves the storage of data on a set of several hard disk drives (the “array”), so that if one of the hard drives on a computer system fails, others in the RAID array may immediately replace the bad drive.  There are at this time at least eleven types of RAID, designated RAID-0 through 7, 10, 53 and 0+1.  RAID arrays are generally categorized according to whether they are “mirrored” (they create exact clones of the drive in question) or “striped” (only parts of the hard drive to be duplicated are put on each of the RAID drives).  The former is slower but complete (a “rebuild”), the latter faster but will not allow a complete restore.  While a mirrored drive will replace a hardware failure on an active hard drive, it will also copy any viruses as well.  There are also two types of caching:  “Write-back, which is faster, signals that a data transfer is complete when the controller cache has received all data in the transaction.  Using “write-through” caching, which is more secure, the controller signals that a data transfer is complete when the disk subsystem has received all the data.  However, there are much less expensive tools for backup these says, due to the low cost of hard drives.  RAID should not be confused with DISK SPANNING, which combines multiple drives, but displays them in the operating system as a single drive.  Four 20Gb drives in RAID would show as four 20gb drives; if they were spanned, they would show as one 80Gb drive.  Spanning provides no data protection, only a convenient way to display multiple drives.  For a truly excellent graphic showing the operation of the various levels of RAID, click HERE.

RAINBOW TABLE: Used to break encryption.  See Hellman.

RAINDROP: A project that Mozilla Labs characterizes as “an open experiment in messaging on the web”.  Introduced in 2009, Raindrop uses the most common browsers to sift conversations from various sources such as e-mail, Twitter and RSS feeds, pulling out the important parts, then having them rise to the top of the list, effectively “personalizing” your inbox.

RAM:  “Random Access Memory”.  This is the memory used to run your computer’s operating system and any programs.  This memory is to be distinguished from the memory on your hard disk drive in three important respects:  First, the RAM is completely emptied when the computer is turned off.  Second, the RAM represents only the amount of memory allowed in the computer to work on various programs and files, while the hard drive includes all of the systems, files, folders and programs that are saved on your computer.  Third, the RAM is generally on separate chips inserted onto the computer’s main circuit board.  The hard drive, on the other hand, is like the file cabinet, the RAM is more like the desk space you have available to spread out the files you are working on. Distinguish this type of temporary memory from CACHE (pronounced “cash”) which is a temporary place for storage of data and instructions between a storage device (a hard disk, for example) and the processor (chip).  RAM comes in various types and capacities, including SIMM, DIMM, SRAM, SDRAM and DDR, DDR-2 and DDR-3 RAM.  See this LINK for a discussion of the various types of RAM and their capabilities.

RARE EARTH METALS:  Seventeen chemical elements in the periodic table found in the earth’s crust which are necessary for the manufacture of laptops, cellphones, MP3 players, electric cars, wind turbines, supermagnets, photovoltiac cells and the like.  They’re actually not so rare, just extremely difficult to extract.  China has a virtual monopoly on companies that can do this.

RASTER GRAPHIC:  See, Vector Graphic.  Also sometimes called a “bitmap graphic.”

RAY TRACING:  A technique for creating high-resolution images.  It uses a library known as Embree, made available for free from Intel.  The problem is that ray tracing uses considerable computation power such as parallel resources.

RC:  A designation for Microsoft software, meaning “Release Candidate.”  This is the stage of development between beta and final release, at which the program is pretty much bug-free and ready-to-go.

RDBMS:  Relational Database Management System.  This is a method of structuring the storage of data into collections of tables that can be logically associated with each other by certain shared attributes (name, value, etc.).  RDBMS such as Microsoft SQL Server go one step further than a simple search by searching through data by considering each attribute as a “set” and defining where several sets “overlap”.  [Think of a series of circles, each a database listing, which intersect at a certain point to reveal data common to all.] Also, by separating the log from the database file, SQL Server makes the search faster and preserves the database from losses due to crashing.  See also, Database.

RDC:  Remote Desktop Connection.  A Windows utility which allows you to connect to your computer remotely, through the use of IP addresses.

RDF:  Stands for “Resource Description Framework”.   RDF is a language for representing information about resources in the WWW.  used as a base by XML web pages to support meta data across many internet applications, making them more human readable and machine understandable.

RDP:  Stands for “Remote Desktop Protocol”.  This is a protocol designed for secure communications between computers in networks using Microsoft Windows Terminal Services.  It provides a secure remote connection into a another network computer for purposes of diagnosis, data transfer, etc.

REAL TIME:  Instantly.  When you chat in a chat room or with tech support, you communicate right then.  This is as opposed to delayed communication, such as posting in a forum or discussion group, where the post is answered later.

REBOOT:  To restart.  The process of re-initializing the operating system software on a computer. WARM reboot means to restart the system software only, without powering down the computer.  COLD reboot means to shut down the power on the system, let it stand for up to 30 seconds to dissipate the static electrical power on the hardware boards, then restart the system hardware & software..

RECORD:  We could be talking about LPs, those large, black plastic disks that held music.  But we’re not.  Instead, a record is a single file in a database program.  Every record has exactly the same information in the same place, called “fields,” so that they can be sorted efficiently.  Think of a box of recipes:  Each 3 x 5 card has the same information fields (e.g. date, category (desert, appetizer), ingredients, instructions, servings and source.) 

RECURSIVE:   As in “we traced this URL with a recursive spider” or “GNU is a recursive acronym” .  This is almost impossible to define without creating further confusion.  In mathematics and computer science, recursion involves creating a class of objects (or methods) by defining a very few simple base cases of the class (or method), and then defining some rules to break down complex cases into simpler cases.  Got that?  The “simple” definition of recursive is that it is a method of defining functions in which the function being defined is applied within its own definition.  [See, that was absolutely no help and reminds me why I had so much trouble with math in high school.]  So, let’s try by example:  Base case:  One’s parents are one’s ancestors.  Recursion “step”:  The parents of one’s ancestors are also one’s ancestors.  If you were unlucky enough to have taken the “new math” in high school, you can think of recursion of a “subset” to a “set”.  Or, in plain English, a recursive definition will define newer objects in terms of previously defined objects of a class.  Further, the recursion construct can be limited by the number of layers or steps that one desires from the base case (in the above example, say, go back no further than great-great-grandparents).  So, a recursive spider would be a software bot that would search the internet for a class of results that would be within a certain number of steps from a base definition while including that definition and the rules for its application.   Or, in the case of the recursive acronym, for GNU, it stands for “GNU’s Not Unix”.  [Thanks, in part, to Wikipedia, which has an excellent definition of a classic “recursive picture” demonstrating the “Droste Effect,” one in which a picture of something is depicted is pictured within another picture of itself, and so on, until resolution makes it impossible to see.  In the Droste advertisement, a nun carries a tray of Droste cocoa, on which is a picture of a nun, in turn, carrying a tray of cocoa, in turn showing the same thing, and so on.]

Now, let’s apply this to computers:  Recursion is a process in which a function calls upon itself as a subroutine.  This allows the function to be repeated several times without reinventing the wheel each time, since it calls itself during each execution.  Functions that incorporate recursion are therefore called recursive functions.  These functions are efficient programming tools, because they use less code, but you must be careful to provide a termination function, otherwise you will program an infinite loop.

Let’s pick an even easier example:  A “recursive acronym” is an abbreviation that refers to itself for it’s definition.  Example:  GNU mean’s “GNU’s Not Unix”; CAVE means “Cave Automated Virtual Environment”; Cygnus means “Cygnus, Your GNU Support”; get it?

READYBOOST:  A function in Windows Vista that allows USB drives to be used as auxiliary random access memory.   It is used in conjunction with Vista’s Super Fetch technology that pre loads files in anticipation of the user’s requirements.

RED HAT:  Refers to a distribution of Linux that is freely downloadable off the Internet.  Redhat was one of the first versions of Linux to be made readily available and made Linux a mainstream product.

RED TEAM:  The name usually given to internal corporate pen testing teams.  See, Pen Testing.

REFRESH RATE:  Refers to the number of times per second that display hardware (like a computer monitor) draws the displayed data, usually measured in Hz (cycles per second).  For example, a 60Hz refresh rate indicates that the screen is redrawn 60 times per second.  Typical monitor refresh rates are 60, 66, 75 and 85Hz.  Sometimes called the “vertical refresh rate” or, for CRTs, the “vertical scan rate”.  Increasing the rate decreases “flickering” on a CRT monitor, reducing eye strain and providing a clearer image; but a refresh rate too high may damage the monitor.   LCD monitors are usually manufactured with a set refresh rate well above the flicker point; LCD monitors produce less flicker than CRTs because the pixels on a LCD screen stay lit longer before they noticeably fade.  For more about monitors and screens, click HERE.

REGISTRY:  The system registry is probably the single most important of Windows.  It is a system-defined database used by the Windows operating system to store configuration, such as the installation of programs, hardware and the like.  Only professionals should edit the registry, because even a slight slip of the keyboard can render your computer completely useless.  For more information about the system registry, click HERE.

REM:  Shorthand for “remark”.  This is used in DOS and BASIC to introduce a comment in a program line and separate it from a command.  Example:  “10 REM This BASIC program shows the use of the PRINT statement”

REMOTE DESKTOP:  A features in Windows that allows a computer, through an ActiveX control and a Web-based process, to remotely access another computer.  Useful if you want to remotely access your office computer, for example.

REPEATER:  An item of computer hardware that boosts the standard strength of a signal on the network so that it can travel beyond its limit.  For example, on an ethernet network, a signal can travel about 100 meters or 328 feet without being boosted by a repeater, further if it is.  See also hubs, bridges.

REPOSITORY:  A catalog or list of packages available for downloading from a single location.  A term used in Linux and elsewhere.

REST:  Representational State Transfer.  A software protocol that allows Web applications to quickly access and manipulate data through simple http calls.

RESTORE:  The process of copying backup files or drives back to the original computer so that no data is lost.  For more, click HERE.

RESTORE PREVIOUS VERSION:  A feature in Windows Vista and Windows 7 that allows the user to restore previous versions of every data file and folder on the computer, much like Restore Point allows the system to be restored to an earlier date point.

RESOURCES:  A reference to the totality of both hardware and software components available for use by a computer system.  As more and more components are used at the same time, their availability becomes limited or exhausted.  When this happens, the program (including the O/S or any of its components) or hardware may become “deadlocked” and freeze as threads or processes (access to which are controlled by something known as semaphores) may attempt to allocate resources already allocated. One indication of system resources used can be seen in the Performance Tab of the Windows Task Manager, under CPU resources.

RF:  Radio Frequency. Refers to devices (such as RFID’s or Zigby) that use radio waves to communicate.

RFI:  Radio Frequency Interference.  Signals which are created (in the normal course of operation) by the electromagnetic radiation that is emitted by electrical currents carrying rapidly changing signals, also florescent lighting.  This type of interference is easily filtered out.

RFID:  This stands for “Radio Frequency Identification Device”.  An RFID is a chip or a length of encoded “tape” that if affixed to an item so that it’s location can be traced.  You may notice that some stores have these strips attached to them, and that they have to be “deactivated” before you leave the store or else an alarm will sound.  Aside from security, these chips often have a dual purpose.  Prior to arriving at the store, these chips on products or on the shipping or warehouse storage boxes or palettes help identify where these products are and how many of them there are.  Wal-Mart was one of the first to introduce the extensive use of RFID in the mid-1990s.  See also NFC.

RGB:  Standard video format for computer monitors, because most video devices such as digital cameras, game machines, etc., produce output in RGB format.  The RGB color model is one in which the primary colors Red, Green and Blue light are added together in various ways to reproduce a broad array of colors.  Output for modern televisions, however, looks better in S-Video format.  Sometimes “Y” is added for yellow, such monitors called RGBY.  For more about monitors and screens, click HERE.

RIA:  Rich Internet Application. A type of web application that can run independently of browsers, can run on any operating system and in many ways works like a traditional desktop application.  (e.g. Flash, Shockwave, Java; Adobe AIR, Curl, Microsoft Silverlight, Mozilla Prism).

RING:  The “security” rings in the Windows O/S (between 3 & 0) which control the degree of privileges granted to specific software (which may include malware) run on the system.  See, SECURITY for more.

RINGTONE:  Also, sometimes, Mastertone, Realtone.  An audio file in MP3, AAC, WMA or other sound format which creates a sound when there is an incoming call, usually on a cell phone.

RIR:   Regional Internet Registry.  A not-for-profit organization that oversees the IP address space (IPv4 and IPv6) across the five separate geographic regions across the globe (ARIN, RIPE, APNIC, LACNIC and AfrNIC) which, together, are known as the NRO (“Number Resource Organization”).  See ARIN, which is the RIR for the United States.  The RIRs were established in the 1990s by the ISPs in response to the rapid growth of the Internet, and tasked with the establishment of consensus and consistent global policies for address space allocations and assignments, among other things.

RISC:  Stands for Reduced Instruction Set Computer.  This is a type of computer architecture (system design) that reduces chip complexity by using simpler instructions to perform complex instructions that were previously performed by CISC (Complex Instruction Set Computer, what else?) computers.  This is done because the microcode layer and associated overhead is eliminated.  It is used often in cell phone processors.  See also ARM and SoC.

RISER BOARD/CARD:  Generically, a printed circuit board that rises perpendicular to the main or mother board on a computer, such as a modem, sound or video card.  See Main Board for more.  Originally, however, riser boards were a type of board specifically used with the older LPX type motherboards for the purpose of adding additional expansion cards to the computer’s architecture.  The subsequent ATX motherboards eliminated riser boards, as the expansion cards could then be connected directly to the computer’s main board without a riser board.

RJ9, RJ45:  Stands for Registered Jack, those plastic connectors at the end of phone (RJ9) and Ethernet (RJ45) cables.  Interestingly, although the RJ9 is the de facto industry standard for wired telephone handsets, the handset jack itself is not an RJ at all since it was never intended to connect directly to the service line, and is actually a “4P4c” connector.

RMU:  Rack Mount Unit, or 1.75 inches of a rack mount.  See also M6 holes and “U”.

ROBOCOPY:  Microsoft says this stands for “Robust File Copy.”  This is a feature in Windows 7 which allows a user to move a cloned document folder (including sub folders) across the network.

ROBOT:  “Bot” for short.  Generally, any browser program which follows hypertext links and accesses web pages, but is not directly under human control.  Example: Spiders, the “harvesting” programs which extract e-mail addresses and other data from web pages and various intelligent web searching programs.

ROBOTS.TXT:  A text file stored in the top level directory  (“TLD”) of a web site to deny access by robots to certain pages or sub-directories of the site.  Only those robots which comply with the Robots Exclusion Standard will be read and obey the commands in this file.

ROBUST:  A term applied to both computer software operating systems and programs that means it performs well under both ordinary as well as unanticipated conditions. A “robust” application can operate for prolonged periods of time without crashing and, if it does, will not affect other programs.

ROKU:  A set-top box allowing NetFlix customers to view Internet delivered movies instantly on their televisions.

RoHS COMPLIANT: Refers to the Restriction of Hazardous Substances Directive (2002/95/EC): Adopted in February 2003 by the European Union and effective on July 1, 2006, this directive restricts the use of six hazardous materials (lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ether) in the manufacture of various types of electronic and electrical equipment.  Often linked with the Waste Electrical & Electronic Equipment Directive (WEEE 2002/96/EC), which sets collection, recycling and recovery targets for electrical goods and is a part of an EC legislative initiative to solve the problem of huge amounts of toxic e-waste generated by electronic equipment.  The WEEE recycling logo is shown above.

ROI:  Return On Investment.  The monetary benefits derived from having spent money, often annualized.  There are many formulas to calculate ROI.

ROM: Read Only Memory.  See Firmware, CD.

ROOT (DIRECTORY):  In a hierarchal computer file system, the first or topmost directory, the directory that includes all of the other directories.  In Windows computers it’s usually the C:\ directory.  It’s like the “root” of a tree, the starting point from which all branches originate. Subdirectories below the root directory are child directories, and any directory above any other directory is a parent directory.

ROOTKIT:  SEE SPYWARE.  A specific type of malicious software that is used by hackers to remotely access infected computers for nefarious purposes.  They aren’t usually discovered by ordinary anti-virus software because they reside in the “root” drive of the computer, hidden from the levels of files which ordinary contain viruses. Because of this, they can disable anti-virus programs.

ROUTERS:  SEE - HUBS, SWITCHES & ROUTERS.

RPC:  Remote Procedure Call.  This service is a part of the Windows operating system that allows Windows’ underlying processes to communicate with one another and across the network with each other.  NEVER disable this service.

RPG:  Role Playing Game.  A game where the player plays the role of someone in a story, sometimes in the character of an avatar. Also, MMORPG, which stands for massively multi-player online role-playing game.

RSA:  A type of encryption algorithm named after its authors/inventors - R. Rivest, A. Shamir and L. Ademan (“A Method for Obtaining Digital Signatures and Public-key Cryptosystems”. CACM 21,2; 1978).

RSS:  Short for “Rich Site Summary”  this term refers to a technology that allows web users to receive ongoing, constantly updated information from several selected sources through one RSS “Feed” that the user subscribes to which selects various sources to be accumulated.  Derived from news syndication, which allows the sharing of news collected from various sources into a single feed (think “UPI” & “AP”).  Basically, an RSS feed allows users to keep up with all their favorite web sites in an automated manner rather than manually checking each one separately.  Every RSS is a feed, but there are other types of feeds besides RSS (e.g. HTML feeds).  See feed.

RTP: Real Time Protocol; also Secure RTP (“SRTP”)  See SIP.

RUBY: Originated and developed in Japan by Yukihiro “Matz” Matsumoto, this is a general purpose object-oriented programming language that combines Perl syntax with Smalltalk-like features.

RUBY ON RAILS:  This is an open source framework for web development using Ruby; it’s principal advantage is speed and ease of use as opposed to Java-based frameworks.

RUGGEDIZED:  Refers to equipment, most often laptops, that have been built to withstand shock resistance, temperature extremes, drops, vibration, dust, moisture, etc. in field or outdoor use.  High end laptops should comply with specifications such as MIL-STD-810F, ASTM D 4169 and IEC 60529.  Toshiba, Panasonic and Fujitsu all make a ruggedized line of laptops.

RUN DLL32:  Run Dll32.exe is a Windows system component that can run dynamic link libraries (“dll’s” which were created when installing programs) and similar software as if they were standalone applications.  Loosely speaking, it’s a utility used as a general tool to launch collections (“libraries”) of task-specific tools. When this file becomes corrupt, it severely damages the Windows operating system and it must be repaired or even reinstalled.

RUN LINE:  The selection on the Windows Start Bar that allows a computer user to run a Windows program or utility.  To be distinguished from a command line, which runs a DOS program from outside the Windows operating system.

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