What was Tet Offensive and why was it important?

As a financial expert with a keen interest in history, I'm often curious about how past events have shaped our current landscape. Could you elaborate on the Tet Offensive and why it holds such significant importance? The conflict appears to be a pivotal moment in history, but I'd like to understand its context and implications in more depth. What were the key factors that led to its occurrence? How did it affect the trajectory of the Vietnam War and global politics? And how does it resonate with us today?