One of the primary advantages of using a source control system is maintaining versions nd tracking changes.
Everytime you checkin a file to the source control, it will create a new version of the file. If you right click on anyfile and select ‘View History’, it will display all versions numbers of the file and also show details like who checked in that version and when was it checked in.
You can select any of the versions in the history and view that version of that file. This will help you to easily revert to an old version of the file if you find that the old version was working better than the new version!
Also, you can select any 2 versions in the history and ‘compare’. This will display the difference between those 2 versions. Depending on the source control software, it will display line by line comparison results. This will help you to easily find which member of the team made what change to the file in each version. So you cannot escape saying ‘I am not the person who made that stupid change” !