I want to add another interesting things  to know, to the list
and thats the browser edition of JVM
a small minimalistinc JVM which has only minimum needed libraries
that can be downloaded from internet,
as fast as flash plugin,
this technology  lets you download the needed libraries later.
so from now on, Java Virtual Machine is not a big size and download
time is no longer a bottle neck for Java Applets
and similar technologies