Definitions and basics

• HTML (hyper-text markup language): a system for formating text for display.  Protocol used for web pages, can include other objects.
• Applet: small application that runs inside a web page, most commonly written using Java.
• Java: a compiled, object oriented computer language that runs in a virtual machine, making it (nearly) platform independent.  Modern Web browsers include this virtual machine.   In web pages it is typically used for writting applets, and the file(s) containing the compiled code are seperate from the webpage itself.  It was (and is) developed by Sun Computers.
• JavaScript: an interpreted, object oriented computer language that can run within a browser.  In web pages it is typically used to add dynamic features, and the code usually resides hidden within the webpage.  It was originally developed by Netscape.
• JAR (java archive record) a special zip file that holds the many files required for a java application.
• Physlet (Physics applet) is a physics oriented applet developed by Wolfgang Christian and collaborators.  Most can be scripted by JavaScript and can communicate with other Physlets using the DataListener protocol. (These are not features of many applets.)