In this presentation we will be exploring Team Foundation Server API. First we will cover the basics by familiarizing ourselves with TFS infrastructure and core API classes. Then we will explore different use cases by building 3 applications that interact with TFS. Finally we will learn how those applications can be tested.We will start off with an application that interacts with the build queue and sends reports when a build fails.By building the second application Build Explorer we will learn to how to trigger builds, modify and clone build definitions. The last application will enable us to gather some statistical data. Specifically, how many tests were added by each team member for a given period of time.