Version Control helps us to keep track of changes made to entities in our project including requirements. In this we can create and manage QC entities while maintaining previous version of those entities in requirements.
To make changes in an entity in a version control enabled project, first we have to check out the entity. When we check out an entity, QC locks the entity, preventing other users from overwriting any changes we make. The checked out version of the entity is not visible to the other user.
We can check out an entity in the following ways:

Checking Out Entities Automatically
Checking Out Entities Manually   _{Your Comment}