TFS is stand for (Team Foundation Server) which is powered by the Microsoft and used for to delivers source control, work item tracking, Team Foundation Build, a team project portal Web site, reporting, and project management capabilities. It also includes a data warehouse where data from work item tracking, source control, builds and testing tools are stored. But by the Microsoft Visual Studio by default Team System servers include build servers and test servers according to the user requirements on your business needs you might choose to deploy some or all of these servers. It also helps you implement your process to increase efficiency and tracks your process to tell you if everyone is following the process and whether you're making progress. It is all about the progress, not the tool. We are software developers, which means every tool we use should advance the goal of making software, as TFS does.