java - What is perm space?

Question

While learning about java memory profiling, I keep seeing the term "perm space" in addition to "heap." I know what the heap is - what's perm space?

Answer 1

It stands for permanent generation:

The permanent generation is special because it holds meta-data describing user classes (classes that are not part of the Java language). Examples of such meta-data are objects describing classes and methods and they are stored in the Permanent Generation. Applications with large code-base can quickly fill up this segment of the heap which will cause java.lang.OutOfMemoryError: PermGen no matter how high your -Xmx and how much memory you have on the machine.