The closure principle has become the foundation of most modern multiple testing procedures. This roundtable discussion will focus on the various aspects of the closure principle motivated by the idea that in many cases, simpler and more powerful closed testing procedures can be performed when they are more specifically tailored to the problem at hand. We will discuss the original closure principle of Marcus, Peritz, and Gabriel, and how modern procedures implement it. We will focus on clinical trials with multiple endpoints to help stir the discussion to the practical applications of multiple testing.