What is compiler?

This program converts source code into machine language at once i.e. by taking whole program into account.

What is interpreter?         

This program converts source code into machine language step by step or line by line.

What is byte code?

The java compiler translate the source code to an intermediate language called byte code. It is platform independent. It is multiple platform byte code and which has just one aspect of Java portability.

What is java virtual machine?

The program written in java language must be compiled and interpreted both. Java language use java compiler to convert source code into byte code and then these codes are interpreted by using java interpreter and this interpreter is known as Java Virtual Machine (JVM) and machine language for JVM is known as byte code and combination of JVM and API is treated as Java Working platform.