CGI programs are the most common way for Web servers to interact dynamically with users. Many HTML pages that contain forms, for example, use a CGI program to process the form's data once it's submitted. Another increasingly common way to provide dynamic feedback for Web users is to include scripts or programs that run on the user's machine rather than the Web server. These programs can be Java applets, Java scripts, or ActiveX controls. These technologies are known collectively as client-side solutions, while the use of CGI is a server-side solution because the processing occurs on the Web server.

One problem with CGI is that each time a CGI script is executed, a new process is started. For busy Web sites, this can slow down the server noticeably. A more efficient solution, but one that it is also more difficult to implement, is to use the server's API, such as ISAPI or NSAPI. Another increasingly popular solution is to use Java servlets.

CGI: Common Gateway Interface 
This CGI page, from the World Wide Web Consortium, provides many links to information on documentation and specifications, discussions in newsgroups, and next generation APIs.

ScriptSearch 
Contains over 5000 scripts for CGI, Perl, C++, Java, JavaScript, Visual Basic, VBScript, AppleScript, and Tcl.

CGI Made Really Easy
Describes how to write CGI scripts to process HTML forms. Also includes links to related information such as specifications, documentation and scripts.

CGI programming in Java
Examples on connecting to CGI programs from Java and using Java to implement CGI programs. Examples are extracted from the book "Core Web Programming" from Prentice Hall Publishers.

Common Gateway Interface (CGI) documentation
The CGI documentation page offers links to various types of reference guides for CGI programmers. The guides include a primer, introductory, handling forms, security issues, interface specifications, and error handling. In addition, there is an archive of CGI programs available via FTP.

Decoding forms with CGI
This NCSA page contains tips and information on decoding forms with CGI. Additionally, there are links to an archive of downloadable decoding software packages.

Programming with HTML forms
This how-to guide describes the three stages in the design and implementation of a HTML forms-based application. Includes HTML syntax and three working examples in C.

Server-side Includes
Contains a chapter from a CGI programming book that explains server-side includes.

The CGI Collection
An interactive collection of functional CGI scripts that help you learn. Search hundreds of CGI-related pages using the CGI-bot.

CGI Tutorial
This tutorial provided by WDVL takes you through the process of creating CGIs.

Intro to CGI
Introduction to CGI is part two of an easy-to-understand four-part series on Web programming.

The CGI Resource Index
Contains a number of links to CGI resources, including programs and scripts, divided into useful categories.