Enol
Enols of ketones can be made on two different sides. It is important to be able to choose which side to react. The side with less substituents is the easiest one to react: it can be made at low temperature with a bulky base. This is called the kinetic enolate. The other side, with more substituents, is more difficult to react. Higher temperatures are needed. This is called the thermodynamic enolate.