Diff programs, or diffing process, means computing and displaying the differences between the contents of files:

Diff programs, or diffing process, means computing and displaying the differences between the contents of files:
* https://en.wiktionary.org/wiki/diffing
* https://en.wikipedia.org/wiki/Diff
* https://en.wikipedia.org/wiki/Comparison_of_file_comparison_tools
Some tools for it:
* Diffchecker - Compare text online to find the difference between two text files: https://www.diffchecker.com/