Packet - A set of data (a collection of bits, including the address, data and control elements) that is processed as a unit in data transmission.

Packet Switching - A method of transferring data in a network where individual packets are accepted by the network and delivered to the prescribed destination. Packets can be distributed in any order because the control data sent at the beginning of the transmission ensures they are interpreted in the correct sequence once received. Because each packet carries its own instructions, it can use any route to reach its destination.

Page - A single (page) file of hypertext mark-up language. A Web site is composed of many pages of information.Page Views: The number of times a Web page is opened, typically measured per person. Page-view statistics often do not include the specifics for frames within those pages. Also, the page-view count generally does not distinguish between unique and repeat visitors.

Page Views - The number of times distinct pages of a Web site are served.

PageRank - Google's proprietary measure of link popularity for Web pages.

Paid Inclusion - Many search engines offer a PFI program to assure frequent spidering or indexing of a site (or Web page). PFI does not guarantee that a site will be ranked highly (or at all) for a given search term. It just offers webmasters the opportunity to quickly incorporate changes to a site into a search engine's index.

Paths - The navigation routes visitors take on a site--a particularly useful measurement of how difficult a site is to maneuver and the popularity of specific pages.

Pay-Per-Click (PPC) Search Engines - This is a traffic generating method where a search engine or directory places your link in their searchable database and charges you a fee every time your URL comes up in a search and it gets clicked on. The amount of the fee that you pay is usually determined by bidding on keywords or keyphrases.

Payment Gateway - A party which provides an interface between Merchant POS systems, Acquirer payment systems, and Issuer payment systems.

PDA (Personal Digital Assistant) - Handheld computing and communication devices.

PDF - A file format exclusive to the Adobe Acrobat Reader that can be downloaded and viewed off-line.

Penalty - A punishment levied against a Web page by a search engine as a result of using an SEO tactic that it doesn't approve of.

Perl (Practical Extraction and Reporting Language) - A scripting language used for text manipulation and popular for writing gateway applications (CGI).

PFI ( Pay for Inclusion) - PFI involves paying to have your Web site visited and indexed by a search engine or directory within a specific period of time.

PHP (Personal Home Pages) - A server-side scripting language for creating dynamic Web pages. Used in conjunction with HTML. When a visitor opens the page, the server processes the PHP commands and then sends the results to the visitor's browser, just as with ASP or ColdFusion. Unlike ASP or ColdFusion, however, PHP is Open Source and cross platform.

PIN (Personal Identification Number) - A number, usually related to a unique payment card or debit card, which must be entered along with the payment card number to make any transaction. The PIN is equivalent in function to a password in that a user cannot use the card without providing the PIN. The SET 1.0 specification does not address cards that require PINs; the SET 2.0 standard will address this issue.

Ping - The TCP/IP service that lets you check to verify that you can reach another network node from your local host. Ping is usually a quick test to ensure that your connection is valid. The command will return the time in milliseconds that a packet takes to make the round trip from your local host to the remote host.

Plug-ins - A software application that allows you to view different information formats in your browser window.

PNG (Portable Network Graphics) - A graphics format designed as the successor to GIF. It features compression, transparency, and progressive loading, like GIF, but it is free of patent restrictions. Current versions of Netscape and MSIE support it.

POP (Point-of-Presence) - A group of modems, routers and other equipment, located in a metropolitan area, allowing subscribers to access the Internet through a local telephone call. Also: POP is an acronym for Post Office Protocol.

POP2 or POP3 (Post Office Protocol) - A protocol designed to allow single user hosts to read e-mail from a server. There are three versions: POP, POP2 and POP3. Later versions are not compatible with earlier versions.

Portal - Similar to a launch pad or a default home page on the Web, a portal is a starting point for Web users.

POS (Point of Sale) - A server that provides an interface between Cardholder software and Acquirer payment systems. It communicates with both cardholder and payment systems using messages that adhere to a specific payment protocol such as SET or SSL. See also Server POS.

Positioning - The process of ordering Web sites or Web pages by a search engine or a directory so that the most relevant sites appear first in the search results for a particular query.

Positioning Technique - A method of modifying a Web page so that search engines (or a particular search engine) treat the page as more relevant to a particular query (or a set of queries).

Post - A transaction from the Merchant that submits a previously authorized transaction to the Acquirer for payment.

Posting - The method of sending e-mail message to a Newsgroup or electronic bulletin board.

Postmaster - The e-mail contact and maintenance person at a site connected to the Internet. Often, but not always, the same as the admin.

PPP (Point to Point Protocol) - A communications protocol that allows dial-up access to Internet over telephone lines.

Protocol - Message formats (rules) that two or more machines must observe to exchange information. To print a document on a network printer, strict protocols must be adhered to or the operation can not proceed.

PUSH (As opposed to PULL technology) - Information is delivered to a desktop or other receiving device in real time as new information becomes available. This is as a result of a user defining areas of interest, industries, and keywords via a personal profile with the PUSH service provider.