IntelliJ IDEA provides various ways to keep track of the changes that you and your team mates introduce to the source code.
Viewing local changes:
Use the editor, where you create your source files, to view, explore and navigate through your local changes within a single file.
Viewing changes of the other team members:
Use the Committed and Incoming tabs to view the changes committed to the repository by the other team members.
Browse through the changes, filtering the range you are interested in.
Explore history of a file in a dedicated view.
Show annotated view of a file to drill deeper into the file history and find changes information for each line of code.