The Source code is the version of a PC program as it is initially composed by a human in a programming language. A compiler is a particular program that converts source code into object code.
However, Computers would not have the ability to understand source codes.
Hence, source codes are compiled using a compiler. Object code is the output of a compiler after it processes source code. The resulting outputs are object codes, which are in a format that can be understood by the computer processor.
In C programming, source codes are saved with the file extension .C, while object codes are saved with the file extension.OBJ