It is commonplace in studios, but also at live concerts, to use many electronic or analogue pieces of equipment at once: sequencers, computers, multi-track recorders, effects, video devices etc.etc. The problem which therefore arises is synchronization, namely, how do we get all these machines to work well together? This is a crucial factor in the quality our work and in the quality of the final product. This synchronization is carried out by using appropriate time codes that act as time references for all the machines involved in the same work session. In this chapter we will get to know the most commonly used time codes and how they are implemented.