How do .class files work?

[Oddblob]

Hello, I'm currently learning Java, pretty basic at the moment, however whenever I'm writing something in Eclipse I can't help but think to myself how do these all get put together and run?
For example, in the popular game Minecraft, if you go into the source of the game there's loads of .class files.
So my question is, what runs all of them, how? Is it the .exe program?

I know quite a lot of people are probably facepalm-ing right now.. but everybody's got to learn somewhere :)

[doWhile]

Learn about the JVM
Java virtual machine - Wikipedia, the free encyclopedia

[quad64bit]

The wiki will obviously give you to most info, so feel to read about it in depth. For those interested in a TL;DR:

The Java Virtual machine is an application which can run bytecode instructions. Bytecode is generated from .java files, and is an optimized set of instructions which the JVM is tuned to execute using native code calls - the JVM itself is written for the native environment on which it executes, but the bytecode is uniform across platforms.