"TDF" most commonly refers to the iconic Tour de France cycling race, a prestigious multi-stage event held annually, or the Theatre Development Fund, a NYC-based non-profit making live performances accessible. It can also refer to TDF (Télédiffusion de France), a French digital infrastructure operator, or the Indian Technology Development Fund for defence self-reliance, or even musical groups like The Dayton Family. The specific meaning depends on the context, but the cycling race and theatre fund are the most prominent.