Let's, Suppose you have 2 applications in which they are sharing the same common.
Dll file for performing some task. After a several period of time an update of application 2 has been released in which they hae also upgraded the Dll file functions too. Now the user will upgrade that Application but after upgrading their application 1 in which the same function is using now that will not work properly because of Update. So to overcome this error .NET comes with the versioning feature.