This section is a very brief explanation of applets. If you know applets and are familiar with Java version numbers, just skip it. If you want to know more about the technologies used for applets, read java.sun.com.
Applets are small programs coded in Java which are downloaded automatically by your browser, if the browser supports applets at all. To execute the applets the browser needs some kind of runtime, called virtual machine, abbreviated by VM. There are several releases of Java, denoted by its version number. Older browsers just support Java 1.0, whereas newer browsers support Java 1.1. Java is backward compatible, i.e. older code will run in a newer runtime, but Java 1.1 code will not run in an 1.0 runtime. As most browser developers have created their own Java runtime, there exists a number of different virtual machines from various vendors, i.e. Apple's, Microsoft's, Sun's, Symantec's, etc., with several version numbers each.
An applet user, i.e. a person who wishes to view an applet, needs to know the Java version supported by his or her browser. An applet developer needs to know the supported VM versions of the target platforms (i.e. the target browsers). The smallest supported Java version is the one he or she has to code the applet. This is even more difficult if you want to support all browsers available. So both need a list of browsers and the Java version number supported by their virtual machines.
There are some pages on the net listing known browsers' VM versions, but these are far from being complete. As Java developer I once needed such a list. First I searched the net for hints. Later I created a Test-Framework and tested even more browsers. Because there is so many different hardware available, the results are incomplete again. For example I did not have any Solaris machines at hand. The list containing known browsers' VM versions has two parts:
Use the Browser's VM Version Test-Framework to test browsers not listed in these version lists, or to make it sure for yourself. Please contact me if you have any new version numbers to report.