Barrons Publishing Dictionary of Computer and Internet Terms 10th

Google Docs a service provided by Google to easily share information that includes spreadsheets and presentations that can be edited by a group of people, such as co-workers.

Google Earth an application provided by Google that allows the user to browse satellite images of the world by street address.

Google whacking (slang, humorous) the sport of trying to find a word so obscure that it occurs on just one of the many web pages indexed by Google.

Gopher a hypertext protocol that was used in the early 1990s, before HTTP. The name “gopher” is a pun on “go for” (i.e., go and get things).

See

gotcha (slang) a pitfall; a feature that leads to mistakes. Compare

MISFEATURE.

.gov a suffix indicating that a web or e-mail address belongs to a government organization. Along with .com, .edu, .int, .net, .org, and .mil, this is one of the original set of Internet top-level domains. Contrast .COM. See also ICANN; TLD.

GPF (General Protection Fault) an error that arises in Microsoft Windows when a program tries to access a location in memory that is not allocated to it. GPFs are usually caused by programming errors such as uninitialized pointers. Software that produces GPFs is defective or improperly configured. See also

GPS (Global Positioning System) a network of satellites allowing users with portable GPS devices to determine precise locations on the surface of the Earth. The portable GPS device measures the exact time taken for signals to reach it from at least four different satellites; from this, the instrument can compute its location.

GPS was developed by the U.S. Department of Defense for military purposes, but it has plenty of civilian applications. Hikers and campers can use it to plot their position on maps. GPS-equipped automobiles can call up computerized maps showing their exact position. Police cars can transmit their exact position to the dispatcher automatically. Boats and ships can use GPS for practically effortless navigation.

To keep GPS from being accurate enough for enemy military use, the Department of Defense originally introduced constantly varying errors that limited GPS’s accuracy to about 300 feet (100 m). This system of intentional errors was called Selective Availability. When Selective Availability was turned off in May 2000, the accuracy became approximately 100 feet (30 m).

GPU (Graphical Processing Unit) an integrated circuit that assists the CPU with graphics-intensive calculations.

gradient fill a fill that is composed of two or more colors. In between the colors is a smooth blending. You are able to rotate the angle of the fill

(linear) or have the blend radiate from a central point (radial). See also

FOUNTAIN FILL; UNIFORM FILL.

FIGURE 120. Gradient fill tool (from Adobe PhotoShop)

grammar checker a part of a word processing program that flags sentences that violate rules of grammar. For example, in Microsoft Word, if you type “They is happy,” the word “is” will be marked with a wavy green underline to indicate that it is not grammatical. However, grammar checkers cannot always be relied on to identify proper usage for your particular document.

See also

grandfather tape a tape that is two generations older than the current data; for example, a backup tape from two days ago if backups are done daily.

See also HARD DISK MANAGEMENT.

graph

1.a graphical display of information, designed to make it easier for the reader to interpret and understand numerical data. See BAR GRAPH and PIE CHART for examples.

2.in mathematics, a set of points connected together in a specific way.

See TOPOLOGY.

graphical user interface (GUI) a way of communicating with the computer by manipulating icons (pictures) and windows with a mouse. Before GUIs became widespread, it was common for computers to operate in a mode where only text (no graphics) could be displayed on the screen.

Xerox developed a machine with a graphical user interface in the 1970s, but the first widely used GUI machine was the Apple Macintosh in 1984. The release of Microsoft Windows 3.0 in 1990 led to widespread use of a graphical user interface on IBM PC-compatible computers. For examples, see MACINTOSH; WINDOWS.

graphics the use of computer output devices, such as screens, printers, and plotters, to produce pictures. The applications of computer graphics include publishing, education, entertainment, and the visualization of computed data (e.g., graphs of mathematical functions).

There are two basic ways to tell a computer how to draw a picture. In vector graphics, the computer is told to put a real or imaginary pen in a particular position and then draw a line a certain distance in a certain direction (or draw a line to another specific point). The alternative is

raster graphics or bitmap graphics, in which the screen or plotting area is divided into a rectangular array of points (called pixels, from “picture cells”), and the computer is told what color each point should be. Computer screens and printers are raster devices, but some graphics software uses vector-style instructions internally so that all lines will appear as sharp as possible on the device actually used to display them.

The amount of fine detail that a particular graphics device can show is called the resolution. The resolution of a printer is usually given in dots per inch; the resolution of a screen is given as the size of the whole image. A good laser printer can print 1200 dots (pixels) per inch, so that an 8 × 10-inch picture is a 9600 × 12,000 array of pixels and contains far more detail than the screen can display.

FIGURE 121. Graphical user interface (Windows)

graphics card a video card that can display graphics as well as text. All modern video cards are graphics cards. See SVGA; VGA.

graphics tablet an alternative to a mouse. A graphics tablet consists of a pressure-sensitive pad on which you draw with a special pen called a STYLUS. This is much more natural than attempting to draw with a mouse. See DRAW PROGRAM; PAINT PROGRAM.

grayed displayed in gray type and not available for selection. If a menu option appears in light gray rather than black type, it cannot be chosen (see Figure 78 on page 140). Menu selections are grayed whenever it is impossible to do the thing they call for (e.g., “Save” may be grayed if there is no data to be saved). See DIMMED.

graylist a spam filtering method in which message delivery is delayed for senders not on the WHITELIST or BLACKLIST. The message is delivered if it is re-sent (in the hope that spammers won’t re-send and legitimate senders will).

FIGURE 122. Graphics tablet (Photo courtesy of Wacom Technology)

grayscale

1.a series of boxes filled with a range of black tints from pure white to 100% black. A grayscale is used to test a printer, monitor, scanner, or printing press.

2.(scanner terminology) the range of grays in an image as measured by the scanner.

3.a description of any image that contains shades of gray as well as black and white.

Greek the alphabet used in ancient and modern Greece, Α Β Γ ... Ω and α β ’γ δ ... ω. Greek letters are often used as mathematical symbols. For the complete Greek alphabet, see page 6. Contrast CYRILLIC; LATIN.

greeking the use of random letters or marks to show the overall appearance of a printed page without showing the actual text. With computers, greeking is used when the page is displayed too small for the text to be readable on the screen.

FIGURE 123. Greeking

Green Book the Philips/Sony standard for multimedia interactive compact discs (not including personal computer software).

Green PC a personal computer that draws little electrical power when idle, even though still turned on. A Green PC typically stops spinning its hard

disk and shuts down power to the monitor if several minutes elapse with no keyboard activity. See also

Gregorian calendar the calendar system presently in use, introduced by Pope Gregory in 1582 and adopted in England in 1752 and in Russia in 1918. It is exactly like the Julian calendar except that years divisible by 100 are not leap years unless they are also divisible by 400. The Gregorian calendar thus follows the earth’s revolution around the sun more accurately than the Julian calendar did. See LEAP YEAR.

grep the UNIX command that reads a text file and outputs all the lines that contain a particular series of characters. For example, the command

grep abc myfile

reads the file myfile and outputs every line that contains “abc.”

Instead of specifying the exact characters to be searched for, you can give a regular expression that defines them. For example,

grep [bB]ill myfile

outputs all the lines that contain either “bill” or “Bill.” See REGULAR EXPRESSION.

The origin of the word grep is disputed, but it may be an abbreviated editing command, g/re/p, where re stands for “regular expression,” g means “global search,” and p means “print” (i.e., display all lines that match the search criteria). Grep programs have been written for other operating systems, such as Windows. Compare FIND.

grid a feature of various draw programs and paint programs that allows lines to be drawn only in certain positions, as if they were drawn on the lines of graph paper. The grid makes it much easier to draw parallel and perpendicular lines, lay out diagrams, and avoid irregular breaks. However, when the grid is turned on, there are positions in which you cannot draw. See also DRAW PROGRAM; PAINT PROGRAM.

grid computing the process of solving computationally complicated problems by distributing parts of the problem to unused capacity on a widely dispersed set of machines that are connected to the Internet.

For examples, see SETI@HOME; TERAGRID; and www.grid.org. For contrast, see

grid system a way of standardizing the layout of many related pages, such as the pages of a multipage document. The designer first draws a grid that will define the possible positions of columns, horizontal divisions, and pictures. Not all the possibilities of the grid are used on any single page, but the grid ensures that column positions do not vary haphazardly, and thereby makes the pages look related.

griefer (slang) a person who plays a multiplayer game or participates in other online group activities for the purpose of making other people miserable. Griefers do not play to win; they do not defeat their opponents

fairly. They play to lose, and they dish out insults, misinformation, and harassment in the process.

Grokster a file sharing service found liable for inducing its users to violate copyright law, in the case Metro-Goldwyn-Mayer Studios et al. v. Grokster (545 U.S. 913 (2005)), decided by the Supreme Court in 2005.

See also NAPSTER.

gross megapixels the total number of megapixels on an image sensor, whether or not all of them are actually used in taking pictures. Contrast

EFFECTIVE MEGAPIXELS.

grounding the establishment of a uniform reference voltage level across several pieces of electrical equipment that are connected together.

In any electrical device, “ground level” is the voltage level to which all other voltages are compared. In most computers, the ground level is connected to the ground pin (the third, rounded pin) of the power plug, and the power line then connects it to the earth itself, thereby assuring that the ground level for all machines is the same. This helps prevent cables from picking up noise or emitting radio-frequency interference. It also reduces the danger of damage from lightning. See

CUIT DIAGRAM SYMBOLS; POWER LINE PROTECTION; RFI PROTECTION.

groupware software that makes it easy for a group of people to work on the same data through a network, by facilitating file sharing and other forms of communication. Lotus Notes is an example of widely used groupware.

GTG chat-room abbreviation for “[I’ve] got to go.”

gTLD (generic Top Level Domain) an identifier such as .com or .edu at the end of a U.S. web address; see www.iana.org/domains/root/db/# for the complete list of possibilities. See also CCTLD; TLD.

GUI see GRAPHICAL USER INTERFACE.

GUID (Globally Unique Identifier) a 128-bit number used by Microsoft WINDOWS to identify a user, software component, or other entity.

GUIDs are most often written as groups of hexadecimal digits in braces, such as:

{79376820-07D0-11CF-A24D-0020AFD79767}

Windows includes an algorithm to generate GUIDs based on an encrypted version of the user’s MAC ADDRESS, which in turn is guaranteed to be unique. (See MAC ADDRESS.) Thus, anyone running Windows who has an Ethernet adapter can create GUIDs that are known to be unique in the entire world. Computers without an Ethernet adapter can generate GUIDs that are likely to be unique but not guaranteed to be.

guideline a nonprinting line that aids in aligning text and other objects in a draw program or page layout program. Some programs allow you to turn

on a snap-to-guidelines feature that causes the guidelines and objects to have a magnetic attraction for each other. See also SNAP-TO-GRID.

guiltware persistent NAGWARE; software that repeatedly asks for a monetary contribution and tries to make you feel guilty if you don’t pay.

Contrast CAREWARE; FREEWARE.

gunk (slang) any undesirable thing that degrades the performance of a computer, such as physical dust, obsolete software, or spyware. Gunk includes well-intentioned utilities that waste CPU time constantly monitoring the status of a modem, network card, or disk drive, as well as

VIRUSES, ADWARE, and other MALWARE.

gutter the blank space between columns of type or between pages of a book.

H

h4x LEETSPEAK for “hacks.” See HACK, especially definition 4.

hack

1.to modify, especially in an improvised way: “This version of the program has been hacked to run under UNIX instead of Windows.”

2.to program a computer, either tediously or enthusiastically: “We spent the whole night hacking.”

3.to break into a computer system or otherwise do mischief: “We’ve been hacked.” See also ETHICAL HACKING.

4.a clever programming technique: “This hack enables a console-mode program to change the title bar of its window.”

When someone in an online game is accused of “hacks,” it means that he or she is suspected of using software bugs or a third-party program to achieve results that the game designers did not intend.

hack attack (slang) a sudden inspiration or compulsion to work on a computer program. Despite what it sounds like, a “hack attack” has nothing to do with computer security violations.

hacker

1.an exceptionally skilled computer programmer.

2.a person who programs computers for recreation or as a hobby.

3.a person who “breaks into” computers without authorization, either for malicious reasons or just to prove it can be done; a CRACKER. See

2600; COMPUTER SECURITY.

hacker ethic the value system of computer enthusiasts who believe in helping each other advance technology by sharing knowledge without immediate concern for making money. See HACKER (definition 2). The hacker ethic has led to valuable cooperative projects such as GNU, LINUX, TEX,

USENET, and the INTERNET.

Usage note: The term hacker ethic is sometimes misappropriated by malicious individuals who believe they are somehow exempt from ordinary rules of ethics (see HACKER, definition 3). In its proper sense, the hacker ethic is an extension of ordinary ethics, not an exemption or loophole.

Hacker Safe see SCANALTERT.

hackish (slang) pertaining to the culture of HACKERs (definitions 1 and 2 and sometimes 3). For instance, using binary numbers on a birthday cake is a hackish thing to do.

hafnium chemical element (atomic number 72) used as an insulator in integrated circuit transistors.

hairline a very thin line, usually about .003 inch wide.

FIGURE 124. Hairline and other line widths

HAL

1.in Windows NT and its derivatives, the Hardware Abstraction Layer, the component of the operating system responsible for low-level interaction with the CPU and closely related hardware.

2.the fictional computer in the movie 2001: A Space Odyssey (1968). Replace each letter of HAL with the next letter in the alphabet to see an amusing coincidence.

half adder a logic circuit that adds two one-digit binary numbers, producing two digits of output. See BINARY ADDITION.

half duplex communication in two directions, but not at the same time. For instance, a two-way radio with a push-to-talk switch is a half duplex device; you cannot hear the other person while you are talking. Contrast

FULL DUPLEX.

halftone the reproduction of a continuous-tone image (containing shades of gray or colors) by converting it into a pattern of very small dots of various sizes. (For an example, look closely at a picture in a newspaper or magazine.) Laser printers and printing presses can print shades of gray only as halftones. See also GRAYSCALE; PHOTOGRAPH.

FIGURE 125. Halftone image (enlarged)

halting problem the problem of determining whether a particular computer program will terminate or will continue forever in an endless loop; a famous theoretical result in computer science.

Consider a computer program A that analyzes other programs; call the analyzed program B. Suppose A can always determine, with complete