Whenever a dancer or an athlete performs amazing feats, it is the consequence of two very interesting cell types: neurons and muscles. When the two of these cell types work together, animals can move in complex ways with surprising control. Not only do they work together to produce movement, they have many traits in common. They both convert chemical signals into electrical information, and then back into chemical information again. This book will examine how neurons process information and communicate to adjacent cells. This book presents how muscle cells know when to contract and how contraction leads to bigger muscles. Finally, the last chapter presents how long-term memories are formed. In all three chapters, some of the original data that have contributed to our understanding of these two fascinating cell types are reproduced to provide supporting evidence for the function of these two cell types.