High performance computing has transformed how science and engineering research is conducted.  Answering a question in 30 minutes that used to take 6 months can quickly change the way one asks questions.  Large computing facilities provide access to some of the world’s largest computing, data, and network resources in the world.  Indeed, the DOE complex has the highest concentration of supercomputing capability in the world.  However, by nature of their existence, making use of the largest computers in the world can be a challenging and unique task. This talk will discuss how supercomputers are unique and explain how that impacts their use.