Team Foundation Server (commonly abbreviated to TFS) is a collaboration platform. You Collaborate different phases of Microsoft’s application life cycle such as source control, team build , project tracking ,testing ,data collection and reporting, team project portal and shared service. It is available either as stand-alone software or as the server side back end platform for Visual Studio Team System (VSTS).

Why is Team Foundation required?

Team Foundation Server enables collaborative environment within the team members to be more productive. Team Foundation Server provides the core collaboration functionality as below: 
    Project management 
    Work item tracking (WIT) 
    Version control 
    Test case management 
    Build automation 
    Virtual lab management

Notes :Image taken from "Team Development with Visual Studio Team Foundation Server"


See Also