Password -- a secret combination of letters and/or numbers needed to log in to a computer system.

Portable Document Format (PDF) -- a file format for Adobe Acrobat. PDF files can be viewed and printed regardless of what application was used to create the file.

Platform -- a means of grouping similar computers. Macintosh computers are one type of platform; so are PCs running DOS.

Portal -- a web site that is intended to be the first place people see when using the web. Typically a "portal site" has a catalog of web sites, a search engine or both. A portal site may also offer e-mail and other services to entice people to use that site as their main point of entry to the web. This is a term coined to describe the large search engine sites such as Yahoo and Lycos.

Protocol -- a formal set of rules that govern the interaction between entities. A protocol can be thought of as a language. If two computers do not use the same network protocol, then they cannot communicate.