The Prime Directive.
It is a core principle for the entirety of the federation, and has been both a guide and a hinderance to many a star trek captain. But what is it? Why is it important? And why is this value of non-interference the foundation for a society that actively seeks out new life and new civilizations, to boldly go where no-one has gone before? Aren't those two actively opposing priorities? 

These are a few questions addressed in this episode where we attempt to scratch the surface of such a fundamental and often complicated directive. We'll reference episodes from Enterprise and Next Generation, with some brief mentions of Voyager and the Original Series.