What is source code or source file and class file?

What is source code or source file:

The code that has been written using any programming language such as C, C++, C# & JAVA etc is known as source code.

The file which contains source code is called source file.

If source code is written in java language than extension of  the file should be .java

What is Class file:

Java compiler does not convert java source code into machine code instead java compiler convert its into byte code.

The file that contains byte code is called class file.