I will give some description with the link, that might help giving an preview what you will see. #1 - <a href="http://en.wikipedia.org/wiki/Jvm#Heap">http://en.wikipedia.org/wiki/Jvm#Heap</a> - It is a very sumarized overview of the Heap, but the entire wiki page is very nice to you get a bit more familar of what happens inside your JVM. To get more familiar with some term used here and other details see also http://en.wikipedia.org/wiki/Java_perfo