B
Byte. Eight bits, equivalent to one character. See also b. See also Binary Numbers and Binary Measurements.
b
Bit. A contraction of 'binary' and 'digit.' All computer information consists of combinations of the binary digits 0 and 1, also referred to as 'off' and 'on' respectively. See also Binary Numbers and Binary Measurements.
backbone
(1) Aka national backbone. A large ISP that has 45 Mb/s DS3 or faster leased lines connecting high speed TCP/IP routers in several cities across a nation, including peering at the major NAPs (Network Access Points). These backbone ISP also have leased lines, usually 1.5 Mb/s DS1s, connecting to routers in smaller towns. The nodes of the backbone ISP are known as POPs (Points of Presence). Smaller ISPs then connect to the backbone ISP. As of 1998, there are roughly 41 backbone ISPs in the US.
 
(2) A.k.a regional backbone. Similar to a national backbone but focusing around an area larger than a state.
backend
(1) The hardware for storing computer data. This includes storage media such as hard disks and floppy disks.
 
(2) The server's programs which are accessed by clients.
backup
To make a copy of live files for archival purposes. Once live files are backed up, the live files may be deleted to make room on the live machine. Alternatively, the backup files may be used as a reference. Alternatively, the backup files may be used to replace the live files if the live files are corrupted, lost, etc.

The first three rules of computer are: backup, backup, backup. You only need to lose data once before you appreciate backing up. Normally backups occur with some combination of daily, weekly, monthly, and annually. The backup storage medium should be rotated and some should be stored off-site.

A given system may remember which files changed since its last backup. If so, then the following options are usually available at the next backup:

BU Type

Data to BU

Data to Mark

Differential Changed since last BU None
Incremental Changed since last BU Data just BU'd
Copy All None
Daily Changed that day None
Full All All
Backup Domain Controller
See domain controller.
bandwidth
The amount of data transmitted at a time. Digital device measure bandwidth in b/s. Analog devices measure bandwidth in MHz. In networks, the bandwidth and latency define the capacity and speed of a network.
baseband transmission
The transmission of one channels (signals) over a single medium (wire). Examples include Ethernet. This is in contrast with broadband transmission which can transmit multiple channels over a single medium. Examples include analog modems and cable TV.

Baseband transmits 0s and 1s directly, thus it only needs to modify the signal on or off some base signal, whether it is voltage, frequency, amplitude, etc.

Broadband transmits an analog wave which can transmit many messages (channels). Different messages can be carried along different frequencies.
baseline
The line formed by the bottoms of letters and words.
BASIC
Beginner's All-purpose Symbolic Instruction Code. An early high-level, procedural programming language.
Basic Input/Output System
See BIOS.
Basic Multilingual Plane
See BMP.
Basic Rate Interface
See BRI.
Bastard Operator From Hell
See BOFH.
batch file
Aka batch program. An unformatted text file that executes commands sequentially when executed. In DOS and Windows, these files have .BAT or .CMD as filename extensions.
baud rate
Switching speed, i.e. the number of transitions per seconds. Usually expressed in b/s.
BBS
Bulletin Board Systems. A computer set up to receive calls & give callers access to files and data. See also anonymous.
bcc
blind carbon copy. In a mass mailing, to send to additional recipients without letting the others know.
BDC
Backup Domain Controller. See domain controller.
BEDO DRAM
Burst Extended Data Output Dynamic Random Access Memory. A type of EDO DRAM that can access four memory addresses in bursts. It has a bus limit of 66 MHz.
Beginning Of File
See BOF.
bells and whistles
A.k.a. bells, whistles, and gongs. Additional features that enrich a program once the program's basic functionality has been coded. Bells and whistles are added for the programmer's sake whereas chrome is added for the user's sake.
beta
A version that is mostly working but is still undergoing development. Alpha versions under go in-house testing while beta versions undergo testing by selected customers.
beveled joint
A corner that ends in a plane that is usually perpendicular to the line bisecting the angle between the two sides. See also miter joint.
Bézier Curve
Named after French mathematician Pierre Bézier, it is a curve defined by the position of anchor points and tangent lines. The anchor points are the ends of path segments. An anchor point at the end of one path segment will have one tangent line. An anchor point at the end of two path segments will have two tangent lines. A tangent line starts at the anchor point. The length and angle of the tangent line affects the shape of its corresponding path segment.
bidi
bidirectional.

(1) See duplex.

(2) Describes a document that has writing that is both LTR (Left-To-Right) and RTL (Right-To-Left). LTR writing systems include Latin, Russian, and Greek alphabets, and Hindu/Arabic numerals. RTL includes Arabic and Hebrew alphabets.
bi-directional
See bidi.
bi-endian
See big-endian
big-endian
Endian refers to the physical order that significant digits are ordered. In big-endian, the most significant (greatest value) digits come first. EG: The decimal number 79 is big-endian because the 7 digit (representing 70) comes first. In hexadecimal, the same value would be 4F as big-endian. In binary, the same value would be 01001111 as big-endian.

The difference between big-endian and little-endian is more common at the byte level than the bit level. EG: A big-endian system stores the decimal value of 20,3006 as two bytes with hexadecimal values of 4F 52, but a little-endian would store the same two bytes as 52 4F.

The argument for little-endian is that if the value of your number increases such that you need another byte, then you just add a byte to the right of your bytes, whereas for big-endian, you would have to shift your bytes to the right and add a new one to the left. This difference can make some operations run more simply and faster.

IBM mainframes, RISC computers, and Motorola (i.e. Apple) processors are big-endian. Intel processors and DEC Alphas are little-endian. Some processors like the Power PC are bi-endian and can do both.

The origin of the word comes from Jonathan Swift's Gulliver's Travels, where the Big Endians, who broke their eggs at the fat end, rebelled against the Liliputian King required that his Little Endian subjects break their eggs at the small end.
big O notation
Aka Landau notation; asymptotic notation. The limiting behavioiur of a function when the argument tends towards infinity. EG: If f(x) = 6*x^4 -3*x^3 +99, then f(x) is said to be on "order of x^4", or O(x^4), because when x gets very big, all the other factors in f(x) become trivial. Here are the most important big O classes:
  • O(1): Constant.
  • O(x): Linear.
  • O(x log x): Polygonal triangulation.
  • O(x^2): Quadratic.
  • O(x^3): Cubic.
  • O(x^k): Polynomial, algebraic.
  • O(k^x): Exponential.
bin
(1) .bin. Mac files that have been converted between ASCII and binary with the MacBinary encoding process. It preserves the file type, icon, and full Mac name by combining the resource fork with the data fork of the file.

(2) Short for binary. It signifies a directory which contains binary files.
binary
(1) Relating to a numbering system with a base of 2. The largest digit usable is one, just as in a decimal system where the largest digit usable is 9. Each digit in a binary number is 2 to the power of the digit's position, with the first position being the power of zero. Machine languages are written in binary.

The following may or may not be helpful in explaining a binary numbering system:

  • Binary counts as follows: 0, 1, 10, 11, 100, 101, 110,.... For comparison, decimal counts as follows: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,....
  • Binary numbers often occur in octets (sets of eight). The positions of the octet may be numbered (from left to right) 7, 6, 5, 4, 3, 2, 1, and 0. The maximum in each position is 2 to that power. The value of each digit in each position would be 2^7=128, 2^6=64, 2^5=32, 2^4=16, 2^3=8, 2^2=4, 2^1=2, and 2^0=1. For comparison, for an octet of decimal numbers, the value of each digit in each position would be 10^7=10000000, 10^6=1000000, 10^5=100000, 10^4=10000, 10^3=1000, 10^2=100, 10^1=10, and 10^0=1.
  • From right to left a binary system has a ones place, a twos place, a fours place, a 16s place, a 32s place, a 64s place, a 128s place, etc. For comparison, from right to left a decimal system has a ones place, a tens place, a hundreds place, a thousands place, a ten thousands place, etc.
  • Given an arbitrary binary number 1010, its decimal equivalent is 1*2^3 + 0*2^2 + 1*2^1 + 0*2^0 = 8 + 0 + 2 + 0 = 10. For comparison, the decimal number 170 = 1*10^2 + 7*10^1 + 0*10^0 = 100 + 70 + 0.
  • A common binary number is an octet where each digit has been set to one: 11111111. In decimal that value is 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255. See also IP.
  • An easy way of manually converting a decimal value into a binary value is iterative division. See iterative division.
  • n2 10000 1111 1110 1101 1100 1011 1010 1001 1000 111 110 101 100 11 10 1 0
    n8 20 17 16 15 14 13 12 11 10 7 6 5 4 3 2 1 0
    n10 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
    n16 10 f e d c b a 9 8 7 6 5 4 3 2 1 0
    2n 65,536 32,768 16,384 8,192 4,096 2,028 1,024 512 256 128 64 32 16 8 4 2 1
    10n 1016 1015
    P(peta)
    1014 1013 1012
    T(terra)
    1011 1010 109
    G(giga)
    108 107 106
    M(mega)
    100,000 10,000 1,000
    K(kilo)
    100
    H(hecto)
    10
    D(deka)
    1

The c/c++/java shorthand for a binary value is to prefix with 0b. EG: This decimal value int y = 12 is the same as this binary value int y = 0b1100.

See also octal and hexadecimal. See also Binary Numbers and Binary.

(2) A function or operator that has two arguments. See also nullary, unary, and ternary.

binary large object
See BLOB.
binary tree
A tree where each node that is not a leaf has two children: a left and a right child. A leaf has null values for left and right children.

The three most common visitation methods (ways to traverse a binary tree) would have the following results with the example binary tree:

Sample binary tree

Name

Method

Result

Inorder  left, root, right ABCDEFGHIJ
Preorder  root, left, right GDBACEFIHJ
Postorder  left, right, root ACBEFDHJIG

See also B-tree.
bind
To have a control connected to a database source.
BIOS
Basic Input/Output System. A boot up program stored permanently on the ROM or EEPROM chip of a computer, usually at address F000. It is the first program invoked at power up. It usually runs POSTs and then searches for the start up disk. To find out which BIOS your system has, watch the screen carefully when you first turn on the computer (use the pause button if it goes by too quickly) or try one of these key combinations when you boot up: CTRL+ALT+S; CTRL+ALT+ESCAPE; DELETE; F8; F10; ALT+F10, or try using msd.exe, a utility that comes with Windows.
bit
See b.
bitmap
See bmp.
bitmap font
Aka screen font. Fonts where each character is stored as a dot by dot map. Since the bitmap is for the font at that particular size, it doesn't look good when scaled up or down. Bitmapped fonts are, however, are processed faster than outline fonts.
BitTorrent
A peer-to-peer file distribution application written by Bram Cohen. It's free, legal, and very easy to use. See BitTorrent.com and BitTorrent [W].
BLOB
Binary Large OBject. A large file (usually an image, sound, or video file).
block
(1) The smallest chunk of memory accessed or transferred by a disk drive. The size of a block is measured in bytes. A block is usually 512 bytes although it can be larger in multiples of 512. See also b.
 
(2) In programming, it is a collection of statement, usually enclosed within {curly brackets}, which can act as a single statement.
blog
Aka weblog. Blogs are evolved online journals or news pages. The content of a blog site is still usually dated and archived. See also my section on Blogs.
blue laser
A laser with a wavelength of 414 nanometers as opposed to the more common red laser with a wavelength of 630 nanometers. If perfected, this could enable the creation of even higher density storage in optical mediums such as CDs and DVDs. Sony put the first blue laser HD TV/DVD recorder/TV tuner on the market in early 2003.
Blue Screen of Death
See BSOD.
Bluetooth
Short range wireless (radio) connectivity between mobile devices and devices to the Internet. Bluetooth devices connect as masters and slaves in small groups called Piconets; Piconets overlap as Scatternets. Bluetooth was developed by Ericsson, IBM, Intel, Nokia and Toshiba. At 1 Mb/sec, Bluetooth is not meant for heavy traffic and is not a substitute for LANs and WANs.
Blu-ray Disc
Aka HD-DVD. An optical disc format that is read and written with blue lasers, thus Blu-ray Discs hold 25 GiB or 50 GiB if dual-layer.
bmp

(1) .bmp or .bmpp. Bitmap. A graphic file format native to Windows. It is rasterized with 24 bits per pixel color. It is used especially for backgrounds and wallpapering. This format may be compressed with RLE.

(2) Bitmap. The concept of representing images or typefaces as dot by dot drawings.

(3) Basic Multilingual Plane. Aka UCS-2. The 2 byte (16 bit) character set used by the Unicode consortium and ISO/IEC.

BNC
British Naval Connector or Bayonet Nut Connector or Bayonet Neill Concelman. A connector used for thin coaxial cable. See also connector, media and 10BASE-X.
BNF
Backus-Naur Form, Backus normal form. A formal notation to describe the syntax of a given formal languages. Originally developed by John Backus and Peter Naur for ALGOL. The meta-symbols of BNF are:
::= meaning "is defined as" 
| meaning "or" 
< > angle brackets surround category names
[ ] square brackets surround optional items
{ } curly brackets surround a list of items
" " double quotes surround literal character 
*       suffix indicating zero or more times
+       suffix indicating one or more times
EG:
<if_statement> ::= if <boolean_expression> then
                       <statement_sequence>
                   [ else
                       <statement_sequence> ]
                   end if ";"
In recent text books, terminal and non-terminal symbols are distinguished by using bold faces for terminals and suppressing < and > around non-terminals. This improves the readability.
if_statement ::= if boolean_expression then
                     statement_sequence
                 [ else
                     statement_sequence ]
                 end if ;
In my notation (described in my About), it would be something like the following:
if booleanExpression then
    statementSequence
[ else
    statementSequence ]
end if ;
For the fun of it here is the BNF description of BNF notation itself:
syntax     ::=  { rule }
rule       ::=  identifier  "::="  expression
expression ::=  term { "|" term }
term       ::=  factor { factor }
factor     ::=  identifier |
                quoted_symbol |
                "("  expression  ")" |
                "["  expression  "]" |
                "{"  expression  "}"
identifier ::=  letter { letter | digit }
quoted_symbol ::= """ { any_character } """
BOF
Beginning Of File. In databases, this is the position prior to the first record in the recordset.
BOFH
Bastard Operator From Hell. A rogue system administrator. Based on the fictional character of the same name created by Simon Travaglia in the early 1990s.
bookmarklet
A short bit of JavaScript code that is the HREF (URL to open) of a link. A bookmarklet can be clicked or saved as a "Favorite" and then clicked. The script should not return a value and different elements within it should be enclosed with void(). EG: <a href="javascript:alert('Hello world!');">my bookmarklet</a>. my bookmarklet. See also JavaScript Links.
boolean
A number that has only two values, 0 or 1, both of which are also respectively referred to as false or true.
Boolean algebra
The mathematical representation of logical operations, i.e. involving whether statements are true or false. Invented by George Boole. See also truth table.
boot
Bootstrap. Boot-Up. When you turn the computer on. It runs POSTs and searches drives for an operating system.
bound
Some item that is connected to another. EG: A control may be bound to a field or column of data.
bound variable
See free variable.
bounding box
The reference frame for animated illustrations. If sequential stills of an animation are not drawn relative to each other, then the animation will appear to jump around.
BPL
Broadband Power Lines. Technology delivering hi-speed Internet connectivity over the power grid. BPL can also be used by utility companies to monitor electricity consumption.
bpp
bits per pixel. A measurement of the color depth of an image since the bpp determines the maximum number of colors an image can have.
 

bpp

Colors per Pixel

Comments

0 2^0 = 1  
1 2^1 = 2 "Monochrome". Sufficient for black and white line art or halftones.
2 2^2 = 4 Sufficient for most grayscale images.
3 2^3 = 8  
4 2^4 = 16  
5 2^5 = 32  
6 2^6 = 64  
7 2^7 = 128  
8 2^8 = 256 Used in VGA. Also sufficient for most grayscale images. 
16 2^16 = 65,536 "High Color"
24 2^24 = 16,777,216 "True Color"
bps
Bits per second. b/s. See also b.
BRB
Be Right Back. See also my article on Chat Room Shorthand.
breadcrumbs
A navigational user interface that tells the user where he is on the site while giving options to go back. The idea is a reference to the breadcrumbs used in the Grimm's fairy tale of Hansel and Gretel. There are at least three kinds of breadcrumbs [ref]
  • 'Path breadcrumb trails are dynamic in that any given page will show a different breadcrumb trail based on how the user reached the page.
  • Attribute breadcrumb trails display meta information showing many different trails representing several possible paths to reach the page.
  • The location breadcrumb trail is a textual representation of a site's structure, e.g. Home > Furniture > Chairs > Leather Chairs.'

See also these off-site links: Breadcrumbs for the sake of Users, Breadcrumbs for All, and Breadcrumbs for Those Using ASP.
BRI
Basic Rate Interface. Aka 2B+D line. An ISDN line that has two bearer or B channels, each at DSO rates of 64kb/s, and a data or D channel.
bridge
A bridge is like a repeater (which connects two network segments while boosting the signal), but a bridge also has two other main functions:
  • A bridge can send some of the data packets to another LAN. In other words it can act as a bridge between two LANs. It implements this in OSI Data Link Layer.
  • A bridge can connect two network segments that are of different media types. EG: The first and second segments may be UTP but the third segment may be thin coaxial cable.
See also my article on Portal Devices.
brightness
The amount of tint (white) in an image. Reducing the brightness increases the amount of tone (black) in an image.
broadband transmission
The transmission of multiple channels (signals) over a single medium (wire). Examples include analog modems and cable TV. This is in contrast with baseband transmission which can only transmit one channel over a single medium, like Ethernet.

Baseband transmits 0s and 1s directly, thus it only needs to modify the signal on or off some base signal, whether it is voltage, frequency, amplitude, etc.

Broadband transmits an analog wave which can transmit many messages (channels). Different messages can be carried along different frequencies.
brouter
A brouter is a combination bridge and router. Like bridges and routers, a brouter connects two or more network segments together.

A brouter first checks incoming data packets to see if they are of a routable protocol. If so then the brouter acts as a router and sends or deletes the packet depending on whether a route for the packet is found. If the packet is a non-routable protocol, then the brouter acts as a bridge and either keeps the packet local or sends it off to a remote LAN.

A brouter maintains both a bridging and routing table. A brouter operates in both the OSI Data Link and Network Layers. See also my article on Portal Devices.
browser
Software that is the go-between the user and web servers and other types of servers on the Internet or intranet. The main function of browsers is to accept HTML files but browsers can often accept other types of internet input such as FTP, Gopher, WAIS, Usenet, telnet, and e-mail.
 
Here are two of the most popular browsers available:
BSD
Berkeley Software Distribution. An operating system that has been distributed since that 1970s. It is a derivative of the original AT&T UNIX operating system. Since 1999, the BSD license changed to make BSD open-source and no-cost software. BSD [W]. BSD.org.
BSOD
Blue Screen of Death. The blue screen that comes up on Microsoft operating systems when some sort of fatal error has occurred.
B-tree
A tree data structure similar to a binary tree, but instead of each node having up to 2 children, a node can instead have a variable number of nodes within a range. EG: In a 2-3 B-tree, nodes can have 2 or 3 nodes. More child nodes result in shorter trees, less frequent balancing, and increased efficiency.
BTW
By The Way.
buffer
(1) An internal memory storage area used to temporarily store input and output info so as to provide a continuous stream of data. This is typically needed for systems operating at different or variant speeds. EG: a video player may continuously buffer 5 seconds of extra video so that the viewer will not notice any interruptions in the video feed.

(2) A buffer also refers to processing or editing of data before it is brought to its destination.
buffer overflow
When a program or process tries to sore more data in a buffer than it was intended to hold. A hacker attack using buffer overflow may try to insert instructions in the extra data.
bug
A glitch or failure in the execution of a program.
Bulletin Board Systems
See BBS.
bump
In a newsgroup, forum, or message board, if someone sees a thread of messages that they have no particular comment about but they like it or think it's important, then they may respond to the thread with the just the word "bump". This basically "bumps" the topic to the top of the forum since many people usually sort threads according to latest response or the most responses. It also saves people from the hassle of having to go over a bunch of messages that have some variation of "I agree" followed by some yada yada.
bus
Aka data bus. The wires, sockets, and circuits which connect the cards together in the system unit of a computer. EG: The Mac 68xxx series were either 16 or 32 bits wide, whereas the Mac Power PC series are 64 bit wide. Bus usually refers to the internal bus, i.e. the internal components of the CPU, as opposed to the expansion bus, which connects expansion boards like PCI cards, to the CPU. Some computers also have a local bus connected right to the processor, for higher speed items such as like video data. The bus and the MHz are two important factors in determining a computers speed and power.
byte
See B.
bytecode
Code that has been compiled for consumption by a virtual machine. Some languages (such as C and C++) take source code (code that programmers type) and compile them into machine code specific for certain "machines" or systems. In contrast, some languages (such as Java and C#) take source code and compile them into bytecode, which is then run by virtual machines which translate the bytecode into machine code specific for that system. Hence the same set of bytecode can be run on different machines. LISP, Icon, and Prolog are other languages that can also make bytecode.

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