Reaction mechanism
A reaction mechanism is writing step by step how a chemical reaction works. Usually, only the overall change can be seen in a reaction. The things made in between react too quickly to be seen. These are called intermediates, and in going from one intermediate to another a transition state is crossed. However, it is important to understand all the steps that make the total change. This is because then one can understand more difficult reactions or try to make a reaction work in a certain way.