PHP

PHP is an HTML-embedded scripting language. Much of its syntax is borrowed from C, Java and Perl with a couple of unique PHP-specific features thrown in. The goal of the language is to allow web developers to write dynamically generated pages quickly. (taken from the PHP manual)

Perl

It (Perl) derives from the ubiquitous C programming language and to a lesser extent from sed, awk, the Unix shell, and at least a dozen other tools and languages. Perl's process, file, and text manipulation facilities make it particularly well-suited for tasks involving quick prototyping, system utilities, software tools, system management tasks, database access, graphical programming, networking, and world wide web programming. These strengths make it especially popular with system administrators and CGI script authors, but mathematicians, geneticists, journalists, and even managers also use Perl. (taken from "perlfaq", http://www.perldoc.com)

Java (Applets & Servlets)

The Java^TM platform is a fundamentally new way of computing, based on the power of networks and the idea that the same software should run on many different kinds of computers, consumer gadgets, and other devices. With Java^TM technology, you can use the same application from any kind of machine -- a PC, a Macintosh computer, a network computer, or even new technologies like Internet screen phones. (taken from "General Documentation", http://java.sun.com)

JavaScript

JavaScript is Netscape's cross-platform, object-oriented scripting language... JavaScript lets you create applications that run over the Internet. Client applications run in a browser, such as Netscape Navigator, and server applications run on a server, such as Netscape Enterprise Server. Using JavaScript, you can create dynamic HTML pages that process user input and maintain persistent data using special objects, files, and relational databases. (taken from "Client-Side JavaScript Guide v1.3", http://developer.netscape.com)