Internet Assigned Numbers Authority. IANA distributes IP addresses to the Regional Internet Registries according to their established needs.  It also coordinates with the IETF and others to assign protocol parameters, and oversee the operation of the DNS.

Internet Corporation for Assigned Names and Numbers. Formed in October 1998 by a broad coalition of the Internet's business, technical, academic, and user communities. Specifically, ICANN coordinates the assignment of Internet domain names, IP address numbers, protocol parameters, and port numbers.

Internet Control Message Protocol. A Layer 3 protocol that is used to notify errors, send control messages, and test whether a destination is reachable. ICMP is part of the TCP/IP protocol suite.
Also see OSI model.

Internet Connection Sharing. A function in Windows XP operating system that enables a computer to act as a gateway to the Internet for other computers using a single Internet connection/subscription.

Institute of Electrical and Electronics Engineers. IEEE is a global technical professional society serving the public interest and members in electrical, electronics, computer, information & other technologies. IEEE has produced popular network standards, i.e. "802" group of standards.
IEEE is pronounced "Eye-triple-E".

High speed interface, up to 400Mbps. Usually used to transfer video and audio files from a capturing device like a camcorder to a computer for editing and format conversion purpose. Its popular name is FireWire.

Internet Engineering Task Force. IETF is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet.

Intermediate Frequency. In radio receiver, RF signal frequencies are converted to a constant lower frequency before detection to overcome frequency instability and poor selectivity of the receiver. This conversion process is called the Super Heterodyne principle. And that constant lower frequency is named IF.
Also see RF.

Interior Gateway Protocol. A generic name used for protocols that are used to exchange routing information between routers within an autonomous system.
Also see routing protocol.

Interior Gateway Routing Protocol. A proprietary protocol that was developed by Cisco, used to exchange routing information between routers within an autonomous system.
Also see routing protocol.

Incumbent Local Exchange Carrier. Refers to established local telecom operators that own existing telecom network infrastructure.
Contrast with CLEC.

Internet Message Access Protocol. A protocol that enables remote management of mailbox and e-mails stored on an e-mail server. Contrary to the de facto standard (that is POP3), IMAP doesn't require messages (e-mails) to be downloaded to a local machine. You can use your favorite e-mail editor and work on mailbox and e-mails as if they were on your harddisk.
The latest version, IMAP4, introduces additional features, of which the most important is keyword searching across e-mails.
Compare with POP3.

IP Multimedia Subsystem. A 3GPP standard that enables multi service delivery over diverse access networks (i.e. GSM, CDMA, 3G, DSL, cable, IP-PBX, etc.) using IETF's SIP that handles interactive user sessions in multimedia communication over packet network. IMS is a key enabler of fixed mobile convergence (FMC).

Part of electromagnetic spectrum below red light. Infrared is shorter than microwave but longer than visible light. Infrared frequency band is in the range of 300 GHz - 400 THz, corresponding to wavelength of 1 mm - 750 nm.
The most common use of infrared is for TV remote control. Infrared also has long been used in night vision equipment. In telecommunication, infrared is used as a short-range, half-duplex, point-to-point, LOS wireless technology that conforms to specifications defined by the IrDA.
Also see LOS and IrDA.

Configuration of a wireless LAN Access Point when it acts as a bridge between wireless LAN and wired LAN.

AC or DC power source that resides on data cable. Examples of inline power uses: telephone cable and PoE.
Also see PoE.

A public network that has worldwide coverage. As a consumer term, Internet refers to popular services like Web browsing, e-mail, chatting, file transfer, Internet messenger, etc.
Compare with Intranet and Extranet.

A network that belongs to a company or an organization and provides access to its resources only to its staff or members.
See picture.

Internet Protocol. The standard protocol that is used for addressing and routing on the Internet. IP is a Layer 3 protocol in the OSI model.
Also see OSI model.

A unique address that is used to identify a computer on the Internet. Current IP address consists of 32 bits written in four sets of decimal numbers separated by a period ("dot") in between.
Based on its scope, IP address is classified into Class A, Class B, and Class C. Based on its application, IP address is classified into public IP address and private IP address. Based on its assignment, IP address is classified into dynamic IP address and static IP address.
See Class A, Class B, and Class C IP addresses. Also see public and private IP addresses. And dynamic and static IP addresses.

Internet Protocol Telephony. IP Telephony or Voice over IP (VoIP) is the technology that enables voice (telephone) calls to be carried over IP network (over LAN or Internet) instead of telephone network (PSTN).
Also see VoIP.

A DOS command that is used to get IP address of a computer in a network.
Also see PING.

A standard protocol that provides authentication and encryption for communications over the Internet. IPSec is used to secure VPN tunnel.
Also see VPN, L2F, PPTP, and L2TP.

IP (Internet Protocol) television. Refers to the transmission of TV signal over IP-based networks, such as the Internet. IPTV expands TV coverage to more devices since it can be accessed by standard TV that is equipped with an adapter, IPTV receiver, PC, PDA, mobile phone, and other Internet devices. IPTV enables more control over the programming and integration with other Internet-related services.
Also see Triple Play.

Current Internet Protocol that uses 32-bit IP address.
See IP address.

Internet Protocol version 6. IPv6 is often touted as the next generation Internet Protocol (IPng). IPv6 is defined by the IETF to replace IPv4 in evolutionary way.
The first reason for IPv6 development is the need for more IP addresses to anticipate the growth of the Internet that may include non-traditional network objects, such as mobile phones, automobiles, home appliances, home electronics, humans, pets, trees, etc. In IPv6, IP address is 128 bits long which inflates the number of available IP addresses from 2³² to 2¹²⁸.
In today's IPv4-dominated world, NAT has been used successfully to overcome the lack of IP (version 4) addresses. Nevertheless, most new networking products support both IPv4 and IPv6. And it has been predicted that in the long run IPv6 will replace IPv4 because it has inherent QoS support and adds many improvements in areas such as routing, security, and network auto configuration.
Also see NAT and QoS.

Internet Protocol Exchange. The Layer 3 protocol in NetWare operating system.

Infrared Data Association. IrDA is an industry association which develops global standard for wireless communications using infrared light. IrDA also refers to a point-to-point, narrow angle (30 cone), ad-hoc data communication standard over short distance (less than 1 meter) that was developed by the Infrared Data Association.
Currently in practice, IrDA is used mainly for file transfer and devices synchronization. However, to support advanced applications, IrDA develops new protocols such as for payment solution.
Based on its data rate, IrDA is divided into several classes as follows:

Most mobile phones and external IrDA adapters support SIR, while most notebooks support FIR. But if they conform to IrDA specifications, all IrDA classes must be interoperable.
Also see ad-hoc network and infrared.

Industry Standard Architecture. A 16-bit bus architecture standard, that was developed by IBM in 1980s, for inserting expansion card to PC motherboard. Now PCI slot replaces ISA bus to add expansion cards to a PC.
Also see PCI.

Integrated Services Digital Network. The first generation of digital broadband technology over telephone network. There are 2 types of ISDN, namely BRI and PRI. BRI has lower data rate of 128 kbps while PRI has higher data rate of E1 (2 Mbps) or T1 (1.5 Mbps).
ISDN still exists but at present telephone subscribers are more interested in DSL technology for their broadband connection.
Also see BRI, PRI, and DSL.

Inter Symbol Interference. The interference from pulses (signals) representing the adjacent symbols.

Industrial, Scientific, and Medical band. Refers to frequency bands in 900 MHz and 2.4 GHz range. The ISM band is unregulated and unlicensed in most countries.
Also see UNII band.

International Organization of Standardization. An international standard body that develops, promotes, and publishes global standards in various fields. ISO also runs certification programs that makes it known to the public.

International Telecommunication Union. A specialized agency under the United Nations that regulates and promotes international telecommunications. Formerly known as CCITT.

Internet Service Provider. Company that sells Internet connections to end users. ISP earns money from Internet subscription. Billing calculation is based on connection time or the number of transferred bytes.