What is a Java ClassLoader?

Question

In a few simple sentences, what is a Java ClassLoader, when is it used and why?

OK, I read a wiki article. ClassLoader loads classes. OK. So if I include jar files a

Answer 1

Class Loaders are a functional component of JVM, which loads class data from the '.class' file or from over the network in to the Method Area in Heap.

Looks like a integral part of the JVM, but as an end java user why should I be concerned? Here is why:

Each class loader has it's own name space and classes invoked by a particular class loader gets into it's name space.

Classes invoked by two different class loaders will not have visibility over each other, resulting in enhanced security.

Class loader parent child delegation mechanism ensures java api classes could never be hacked by unauthorized code.

For details look here