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P

Packet Switching
The method used to move data around on the Internet. In packet switching, all the data coming out of a machine is broken up into chunks, each chunk has the address of where it came from and where it is going. This enables chunks of data from many different sources to co-mingle on the same lines, and be sorted and directed along different routes by special machines along the way. This way many people can use the same lines at the same time.
You might think of several caravans of trucks all using the same road system to carry materials.

Palmtop
A palmtop (or PDA, personal digital assistant) is basically a computer in the form of an electronic organiser. They are becoming increasingly powerful and can be used as an alternative to laptops, though their keyboards and displays are much smaller.

Password
A string of digits or characters providing confidential authentication information.

Payment Gateway
A system that provides online e-commerce facilities to merchants on the Internet that links directly into a bank’s financial system.

PC
Personal computer.

PCN (personal communications network)
A digital network technology operated by some of the mobile phone operators.

PDF (Portable Document Format)
A file format designed to enable printing and viewing of documents with all their formatting (typefaces, images, layout, etc.) appearing the same regardless of what operating system is used, so a PDF document should look the same on Windows, Macintosh, Linux, OS/2, etc. The PDF format is based on the widely used Postscript document-description language. Both PDF and Postscript were developed by the Adobe Corporation.

Peer-to-peer (P2P)
One of the simplest network arrangements, involving linking a series of computers together without the use of a server.

Peripheral
A peripheral is anything that is not part of the main computer unit, such as the keyboard, monitor or printer.

PERL (Practical Extraction and Reporting Language)
A popular language for web scripting (used to create web pages and web sites). Although Perl can be used on any system, it is usually associated with Unix/Linux.

Ping
To check if a server is running. From the sound that a sonar system makes in movies, you k now when they are searching for a submarine.

PHP (Hypertext Pre-processor)
A popular scripting language supported by Unix/Linux and Windows systems.

Plug and play
A Windows option that allows multimedia peripherals, such as a CD-ROM drive, to be automatically recognised and set up by the operating system.

Plug-in
A (usually small) piece of software that adds features to a larger piece of software. Common examples are plug-ins for the Netscape® browser and web server. Adobe Photoshop® also uses plug-ins.

PNG (Portable Network Graphics)
PNG is a graphics format specifically designed for use on the World Wide Web. PNG enable compression of images without any loss of quality, including high-resolution images. Another important feature of PNG is that anyone may create software that works with PNG images without paying any fees - the PNG standard is free of any licensing costs.

Portal
A web site that is used to get to another site and a range of services. Scottish-Enterprise.com is a portal site.

POP
Point of Presence. Where your Internet Service Provider physically connects to the main internet network. Also stands for Post Office Protocol, the agreed standard for downloading email messages.

Portal
A website that acts as a comprehensive information source covering a specific sector or subject, and which is used to get to another site and a range of services. Scottish-Enterprise.com is a portal site.

Posting
A newsgroup contribution. Also known as an article.

Proxy server
An intermediary application that sits between a client and a server, and which stores and forwards requests and information. Often used in conjunction with a firewall to monitor Internet traffic and activity.

Proprietary
A proprietary operating system is one that can only be used on one brand of computer and uses software especially written for that system, for instance Apple OS can only be used on Apple Macintosh computers.

Protocol
The set of rules governing the format and control of messages being sent around a network.