The terms program and process are often used interchangeably. However, there are subtle differences:
- Program = source code and/or compiled machine code. The instructions that tell the computer what to do.
- Fixed storage size
- Process = instance of a running program. The code loaded into memory, operating and working on data
- Variable storage size (in working memory)
- Includes the storage requirements of the loaded program plus its data
A unique pid (process ID) is assigned by the OS kernel to each process as an index for various data relating to the process