what is bytecode in java and who executes the bytecode in java code example

Example 1: what is bytecode in java

When a javac compiler compiler compiles a class it generates .class file. 
This .class file contains set of
instructions called byte code. Byte code is a machine independent language 
and contains set of
instructions which are to be executed only by JVM. JVM can understand 
this byte codes.

Example 2: run java bytecode

// Don't usee .class at the end of class file name
java ClassFileName //--in file path-- if file doesn't have package
java PackageName.ClassFileName //--in package path-- if file have package