P

Packet

A packet is unit of information that your workstations and other equipment send to each other over the network. When information is sent from a computer (for example a text file), it is transmitted over the network as a series of packets.

A packet consists of a set of bits forming a single block of data, containing a header which consists of control information such as sender, receiver, and error-control data, as well as the message itself. Because they are similar units of network data, the terms packet and frame have become interchangeable.

Information moves around the Internet in 'packets'; chunks of data each with their own destination address. Think of packets as sealed envelopes containing data, with addresses written on them. They all go through the system, and usually end up at the correct destination. The more envelopes the system must handle, the slower the process becomes.

Also see Bit Frame Hub Network Router Switch

Page

A World Wide Web 'page' is the name given to a basic Web document, such as the one you are viewing at the moment.

PAP

(Password Authentication Protocol). PAP is the protocol that verifies a username and password for PPP connections. This protocol is used if the more extensive CHAP is not available.

Also see CHAP PPP Protocol

parameter entity

A special entity type reserved for use in a document's DTD that is designed to hold lists of attributes and content models.

PARENT element

An element that has one or more elements nested within it. Elements nested within a PARENT element are called CHILD elements.

participating resource

Any resource that is part of a link; all resources can potentially be part of a link, and a resource becomes a participating resource only when a locator is used to include it as part of a link.

pattern

An XSL convention that describes the portion of a construction rule that identifies the element in a document that receives the rule's formatting (action).

PC

(Personal Computer). Although PC is now the term generally used for any personal computer, the original PC standard was developed by IBM.

PC Card

The PCMCIA created a 16-bit socket into which credit card-sized cards are plugged: these are commonly known as PC cards. The ports on these cards attach, for example, modems, sound cards and hard disks to portable computers.

Also see Modem NIC Port PCMCIA

PCDATA (parsed character data)

Element content that comprises just plain text.

PCI

(Peripheral Component Interconnect). sockets are used in all Pentium desktop PCs. PCI sockets provide a much higher performance than ISA, this is essential to get the most out of modern high performance expansion cards. PCI sockets are about 9cm long. 3Com PCI cards support either 10Mbps or 10/100Mbps networking.

Also see Ethernet Fast Ethernet ISA NIC Mbps PC

PCMCIA

(Personal Computer Memory Card International Association). This non-profit making organization was set up in 1989 to standardize a method for connecting equipment to portable computers.

Also see PC Card

Peer-to-Peer network

A peer-to-peer network is one in which workstations (such as PCs) can share information and each other's resources without relying on a centralized server. For example, in a network of four PCs and one hub, it is possible to allow files on all four PCs to be accessed from any other PC.

Also see Client/Server Network Hub Network PC Server

PING

(Packet INternet Groper). A test of the path between the managed device and another device on an IP network that responds to IP (Internet Protocol) packets. During a ping test, the managed device sends ICMP (Internet Control Message Protocol) echo request packets to another node with the specified IP address and waits for echo response packets to return. The node must be capable of receiving and responding to ICMP packets.

Also see IP Packet Protocol

PKZIP or PKUNZIP

Utilities for easily compressing and uncompressing DOS and Windows files. They use the .zip filename extension.

Plug-in

There are many things that your browser can do such as displaying images and web pages. Other things are beyond its capabilities and that's where the plug-ins are introduced. Shockwave and RealAudio are examples of plug-ins required for audio and video.

POP in reference to WAN

(Point Of Presence). The point in a WAN that connects local telephone calls to the network.

Also see WAN

POP in reference to store-and-forward

(Post Office Protocol). Provides a store-and-forward service, intended to move E-mail on demand from an intermediate server to a single destination machine, usually a PC or Macintosh.

Port

A socket from where data can enter and leave a computer, or a networking device. On a personal computer, the serial (console) and parallel ports are for plugging in communications lines to equipment such as modems, routers and printers.

Also see Internetwork Modem Router

POTS

(Plain Old Telephone Service). POTS refers to a basic telephone connection to the public switched network.

Power Adapter

A power adapter is a transformer that converts the alternating current (AC) from a wall outlet, into direct current (DC) required by an electronic device.

PPP

(Point to Point Protocol) PPP is a kind of Internet connection that allows a computer to use Internet protocols to become a part of the Internet. Requires a modem, a standard telephone line and an account from a service provider.

Also see Internet ISP Multilink PPP

PPTP

(Point-to-Point Tunneling Protocol). A protocol that allows a workstation to establish a secure multi-protocol connection to a remote, private network via a locally dialed ISP account.

Also see ISP Protocol VPN

DOM (presentation-based markup)

Markup that describes content mainly designed to be displayed by a device for a user. HTML can be defined as presentation-based markup because its primary goal is to describe content that a user will view with a Web browser of some kind.

PRI

(Primary Rate Interface). A PRI line is one of two access methods to ISDN; BRI is the other. In North America PRI consists of twenty-three 64 Kbps B channels and one 64 Kbps D channel (known as 23B+D). The European PRI consists of 30 Kbps B channels and one 64 Kbps D channel (known as 30B+D).

Also see B Channel BRI D Channel Kbps ISDN

processing instructions (PIs)

An XML convention that allows instructions to be passed from the document directly through the parser to the display software to instruct the software on how to process the entire document or just a part of it. PIs can be placed in any location in an XML document.

Protocol

Method by which computers communicate to each other over the Internet in order to provide a service.

In networking, a protocol is a formal set of rules and conventions developed by international standards bodies that govern how devices on a network exchange data. A protocol defines format, timing, control and sequence of data in a network.

Also see FTP HTTP IP Network NNTP POP PPP SLIP SMTP TCP

PSTN

(Public Switched Telephone Network). The telephone network ubiquitous over the world. Its components are telephones, RJ-11 twisted-pair cabling, and the central office. PSTN is also called POTS (plain old telephone service). The main reason PSTN has not be replaced with a newer technology such as ISDN is that PSTN works when electrical power is out. ISDN requires a separate power supply.

Also see ISDN POTS RJ-11 Twisted pair (TP)

Public Access Provider

An organization that provides Internet access for individuals or other organizations, often for a fee.

Public Domain

Refers to software that anybody can use or modify without authorisation.

Also see Freeware Shareware