Task-based Language Teaching (hereafter TBLT) is the latest development of Communicative language Teaching (henceforth CLT) that many unreal communicative activities have appeared in communicative elassroom teaching. TBLT leads students to learn English by fulfilling a real-task in order to improve their ability of using English. It emphasizes on learner-centered. This dissertation introduces the origin, principles, steps of TBLT, with the aim of providing a clear picture of tasks and TBLT. TBLT: challenge and change in English teaching, new approach, new gain.