Why was there a Tet Offensive?

Could you elaborate on the reasons behind the Tet Offensive? Was it a strategic move by the North Vietnamese forces to gain an upper hand in the Vietnam War? Or was it a desperate attempt to change the momentum of the conflict? What were the specific objectives and motivations behind this offensive, and how did it ultimately impact the war's outcome? Understanding the context and rationale behind this significant event in history is crucial for grasping the complexities of the Vietnam War.