Barrons Publishing Dictionary of Computer and Internet Terms 10th

Internet a cooperative message-forwarding system linking computer networks all over the world. Users of the Internet can view information on the World Wide Web, exchange electronic mail, participate in electronic discussion forums (newsgroups), send files from any computer to any other via FTP, or HTTP, and even use each other’s computers directly if they have appropriate passwords. See ELECTRONIC MAIL; FINGER; FTP;

HTTP; NEWSGROUP; RLOGIN; TELNET; TLD; URL; WORLD WIDE WEB.

Every machine on the Internet has an address. For example, the address

beetle.ai.uga.edu

means:

beetle machine (“beetle”)

ai subnetwork (Artificial Intelligence Lab) uga site (University of Georgia)

edu type of site (U.S. educational)

Here beetle.ai.uga.edu is a domain address that gets translated into a numeric IP address, such as 128.192.12.9, by the network itself. See IP ADDRESS; TCP/IP.

The cost of running the Internet is paid largely by the sites that receive messages, and the sites that pass them along, not by the sites that send messages out. This has important legal and ethical implications.

Unsolicited advertising via e-mail or in newsgroups is almost always unwelcome, as is any self-serving misuse of electronic communications, because the sender of the material is not paying the cost of distributing it. For further ethical guidelines see COMPUTER ETHICS; SPAM; USENET.

The Internet grew out of the ARPAnet (a U.S. Defense Department experimental network) as well as BITNET, Usenet, and other wide area networks. See USENET; WIDE-AREA NETWORK. Contrast INTRANET.

Usage note: Many people confuse the Internet with the World Wide Web, which is only one of several forms of communication that take place on the Internet.

Internet 2 a consortium of universities working with business and government to create a high-performance successor to the original INTERNET. For more information see www.internet2.org.

Internet cafe a small business selling Internet and computer use by the minute or hour. Most Internet cafes also offer other services including everything from food to live musical performances.

Internet casino see GAMBLING.

Internet Content Rating Association see ICRA.

Internet Explorer the World Wide Web BROWSER included in Microsoft Windows; a derivative of MOSAIC. Compare FIREFOX; OPERA.

FIGURE 140. Interpolation (resampling) to enlarge an image

interrupt an instruction that tells a microprocessor to put aside what it is doing and call a specified routine. The processor resumes its original work when the interrupt service routine finishes. Interrupts are used for two main purposes:

1.to deal with hardware events such as a key being pressed or a character arriving through a serial port. These events cannot be ignored; the incoming data must be either processed immediately or stored in a buffer.

2.to call subroutines that are provided by the hardware or operating system. On the PC, most DOS and BIOS services are called through interrupts rather than through the ordinary instruction for calling a subroutine. Windows services, however, are called as ordinary subroutines.

These correspond to the two main ways of causing an interrupt: by receiving a signal from outside the microprocessor (a hardware interrupt) or by executing a machine instruction (a software interrupt).

interrupt service routine see INTERRUPT.

intersection the set of elements that are in both of two other sets. For example, the intersection of {a, b, c} with {c, b, r} is {b, c}.

interword spacing the spacing between words, sometimes called

WORDSPACING.

intranet the opposite of INTERNET; a network confined to a single organization (but not necessarily a single site). Intranets often include web pages, so a web browser can be used to view the content. This makes the intranet appear just the same as part of the World Wide Web; the only difference is that it is not accessible to those outside the organization. Keeping it separate from the outside world is essential if it carries confidential data, such as internal business records. Contrast EXTRANET.

Intuit a leading producer of personal financial software (the program Quicken). Web address: www.intuit.com.

intuitive obvious without conscious thought. The operation of a piece of software is said to be intuitive if the operation fits the task so well that

the user can guess how to perform common operations without consulting manuals or pausing to figure things out. Compare USER-FRIENDLY.

invalid media disks or tapes that cannot be used because of physical defects or because they have been partly erased by a magnetic field. In the latter case the media can be formatted (erased) and used again. See also ABORT; FAIL; RETRY.

invert

1.to turn an image into a photographic negative of itself, substituting black for white and white for black, and changing colors to their complements. Compare REVERSE.

2.(less commonly) to turn an image upside down. For other senses, see

INVERTER.

FIGURE 141. Inverted photograph

inverter

1.a NOT gate. See NOT GATE.

2.a device that converts direct current to alternating current for power supply purposes (e.g., to power a computer from a car battery).

invisible watermark a code secretly hidden in a picture to carry copyright information or other secret messages. An invisible watermark consists of a very slight change of contrast over large areas of the picture, invisible to the human eye, even fainter than the watermark on a piece of paper. Suitable software can recover the invisible watermark even if the image has been printed out, photographed, and scanned in again. See

STEGANOGRAPHY.

Iomega manufacturer of Zip drives and other portable storage devices. Their corporate web site is at www.iomega.com.

IOW online abbreviation for “in other words.”

IP

1.Internet Protocol. See IP ADDRESS; IPV4, IPV6; TCP/IP.

2.intellectual property (i.e., patents, copyrights, and trademarks, especially patented or copyrighted designs for components of equipment or software).

IP address, IP number (Internet Protocol address) the numeric address of a machine, in the format used on the Internet (IPv4 or IPv6). For example, the IPv4 address of one of the University of Georgia’s computers is 128.192.76.80. Convert each of the four numbers into binary, and you get the true 32-bit binary address, which can also be written as an 8-digit hexadecimal number.

Three blocks of IPv4 addresses are reserved for private networks and will never be officially assigned. Therefore, if you must make up an unofficial IP address, you should choose it from one of these blocks. They are 10.0.0.0–10.255.255.255, 172.16.0.0–172.16.255.255, and 192.168.0.0–192.168.255.255. The address 127.0.0.1 on any machine connects it back to itself.

IPv6, a newer version of the protocol, uses 128-bit instead of 32-bit addresses, so that a much larger number of addresses is available. The packet format is different in a number of ways that make routing more efficient.

Contrast DOMAIN ADDRESS; MAC ADDRESS. See also

ADDRESS; INTERNET; STATIC IP ADDRESS.

IP spoofing see SPOOFING.

IP telephony see INTERNET TELEPHONY.

iPhone popular portable phone, web browser, and music and video player from APPLE.

IPO (Initial Public Offering) the first sale of a corporation’s stock to the public. Innovative computer companies have often begun as privately held corporations, motivating employees by offering stock options that become valuable after the IPO if the market price rises. Outside investors who buy stock soon after the IPO will profit from further increases in the stock price. However, this type of investment is very risky because there is no guarantee the stock price will rise.

iPod a portable audio and video player introduced by APPLE in 2001; one of the many brands of portable music player. The iPod plays MP3 and many other file formats, including videos. The iPod Touch specifically can download applications such as calendars or even games, and is integrated with Apple’s iTunes store. See ITUNES; MP3 PLAYER.

IPTV (Internet Protocol Television) a system for transmitting television signals on request. Unlike traditional broadcast signals, which send all channels to all customers, an IPTV system conserves bandwidth by only sending signals for channels that customers have requested. However, traditional Internet transmission sends a separate signal for each user, so broadcast television signals would consume excessive bandwidth if they were sent this way. Instead, IPTV signals for multiple users are combined into a multicast signal, which contains one copy of the broadcast signal as well as the addresses of those users to whom the signal is to be

sent. As the signal gets closer to the users it is split into separate signals for each user.

IPv4, IPv6 older and newer versions of the Internet Protocol, the protocol for routing traffic through large networks. IPv4 and IPv6 were introduced in 1981 and 1994 respectively. As of the date this book was written, IPv4 was still predominant. See IP ADDRESS.

IPv6 version 6 of the Internet Protocol, which will provide for improvements in routing network traffic and will increase the number of available network addresses. There will be a transition period when this version will gradually replace the current version (IPv4). See www.ipv6.org. See also PROTOCOL.

IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) a data transmission protocol developed by Novell and widely used in local-area networking. See PROTOCOL. Contrast ATM; NETBEUI; TCP/IP.

<JohnBoy> Does anybody know where I can get some information about SCSI? <Gweep> Hello, John Boy!

<JohnBoy> Hello, Gweep!

<Hermes> There’s a newsgroup called comp.periphs.scsi. Look there. <JohnBoy> Thanks, Hermes.

<Gweep> What’s a newsgroup?

FIGURE 142. IRC session

IRC (Internet Relay Chat) a multi-user conversation conducted over the Internet in real time. Figure 142 shows what a chat session looks like. Numerous CHANNELS (conversation forums) exist. Participants normally identify themselves by nicknames.

In addition to typing remarks for transmission to the other participants, the IRC user can type commands such as /list to see what channels are available, /join #frogs to join a channel called frogs or create it if it doesn’t exist, and /bye to sign off. See also AIM; CHAT ROOM.

IRL online abbreviation for “in real life,” meaning the mundane, real, physical world as opposed to the glamorous exciting life in CYBERSPACE.

IRQ (Interrupt Request) a type of bus signal used on PC-compatible computers to allow input-output devices to interrupt the CPU.

ISA (Industry-Standard Architecture) a term often used to describe the conventional IBM PC AT (16-bit) bus and the associated card edge connector, as opposed to EISA. See BUS; EISA.

ISA slot a slot in a computer where ISA accessories can be added.

iSCSI (Internet SCSI) a method of communicating with a disk drive on a server using the same protocol as if it were attached to a SCSI port, but wrapping the SCSI data in Ethernet packets. Compare SCSI.

ISDN (Integrated Services Digital Network) a type of all-digital telephone service that can transmit computer data (e.g., for Internet connections) as well as voice, with a maximum speed of 128 kbps. ISDN service began in the United States in 1988 but has largely been superseded by DSL, which obtains higher communication speeds over conventional telephone lines. See DSL; T1 LINE; T3 LINE.

ISO

1.International Organization for Standardization (abbreviated ISO in all languages), an organization that sets standards for many industries. For example, there are ISO standards for the Pascal and Prolog programming languages and for sizes of printer paper. See also ANSI; PAPER SIZES (ISO).

2.online abbreviation for “in search of.”

3.a system for rating the sensitivity (speed) of photographic film or CCDs, based on an ISO standard, equivalent to the older ASA system. An ISO 100 film or CCD will make a correctly exposed picture of a sunlit landscape when exposed for 1/100 second at f/16.

ISO 9000 an ISO standard specifying various ways of ensuring the quality of manufactured products. It does not denote any specific computer technology.

ISO 9660 the basic standard format for recording computer data on compact discs (CD-ROMs). Unlike most disk formats, CD-ROMs are not tied to the operating system of a particular computer; any computer can read the data files from any standard CD-ROM. (Software recorded on the CD-ROM may of course require a specific computer in order to run.) ISO 9660 format supersedes the earlier High Sierra format, with which it is closely compatible. See JOLIET FILE SYSTEM; ROCK RIDGE.

ISO paper sizes see PAPER SIZES (ISO).

ISP (Internet service provider) a company that provides accounts allowing customers to access the Internet. See

PROVIDER.

ISV (independent software vendor) a company that writes software independently of the company selling the hardware.

IT (information technology) computers and electronic communication.

italics letters slanted to the right and designed with a more calligraphic feel than their roman counterparts. This sentence is set in italics. Italics are used for emphasis, for setting the titles of books and articles, and for foreign words. Italic type corresponds to underlining on a typewriter.

Itanium a family of Intel 64-bit microprocessors implementing the IA-64 architecture, introduced in 2001. See IA-64.

iteration the process of repeating a particular action. For examples see FOR; WHILE. Contrast RECURSION, in which instead of merely being repeated, the action creates another action of the same type within itself.

ITU (International Telecommunication Union) an organization headquartered in Geneva, Switzerland, that sets standards for electronic communication technology. For more information see the web page www.itu.int.

ITU-T the telecommunication section of the ITU, formerly known as the CCITT.

iTunes an online store integrated with iPods to allow for easy purchase of music and audiobooks, as well as movies, television shows, and applications. See APPLE; IPOD.

iWork a set of software applications (word processing, spreadsheets, and presentations) provided by APPLE.

J

J# (pronounced “J sharp”) a programming language very similar to JAVA but implemented in the Microsoft .NET Framework; essentially a combination of Java and C#. Most Java 1.1 programs will run unaltered in J#, and in addition, the full functionality of the .NET Framework is available.

See C#; .NET FRAMEWORK.

jack a connector into which a plug can be inserted.

FIGURE 143. Jaggies (stairsteps) in an improperly-sized bitmap

jaggies the property of an improperly sized bitmap that shows the image broken into blocky squares. See ANTIALIASING; BITMAP; PIXELATE; RESOLUTION.

Japanese writing see KANA.

JAR file (Java Archive) a file containing a collection of Java class files that can be downloaded more efficiently than would be possible if each file were downloaded separately.

Jargon File a glossary of computer terms begun at Stanford University in 1975, extensively enlarged at MIT, and eventually published, in highly revised form, as The New Hacker’s Dictionary, by Eric S. Raymond (MIT Press, 3rd edition, 1996). Versions are also available on the World Wide Web. The Jargon File is important because it is one of the first instances of computer enthusiasts functioning as a cultural movement.

Java a programming language developed at Sun Microsystems in the mid1990s to enable networked computers to transmit computations to each other, not just data. For example, an Internet user can connect to a Java APPLET (program) on the World Wide Web, download it, and run it, all at the click of a mouse, using a Java-compatible WEB BROWSER. Applets can include features such as animation. Figure 144 shows an example of a Java program.

Java is designed for OBJECT-ORIENTED PROGRAMMING. The language is extensible: classes are defined in terms of other more general classes,