We have many different types of biological processes that are catalyzed by enzymes. And what these enzymes do is they speed up the rates of these biological reactions. Now, because enzymes affect the rates, to actually understand how enzymes work, we have to understand the rates of these enzymecatalyzed reactions. And in fact, enzyme kinetics is the study of the rates of these enzyme catalyzed reactions that take place inside our body. Now, in the next lecture we're going to begin our study of enzyme kinetics. But in this lecture we're going to remember some basic information about how to actually represent and express the rates of chemical reactions.