In stereochemistry topic, we will learn more different types of isomers. To clarify the concepts, it is a good idea to have a summary about the isomers in organic chemistry. There are two major types of isomers, constitutional isomers and stereoisomers. We have had detailed discussions on constitutional isomers in Chapter 2, and will focus on stereoisomers in this chapter. Stereoisomers are molecules with same bonding, but groups are in different spatial arrangement. At beginning of this chapter, we will learn more about geometric isomers in alkenes and the E/Z naming system. Then we will move on to a brand new category of stereoisomers, the isomers with chirality center. The flowchart here (Fig. 5.1a) show the correlation and difference between different types of isomers (pay attention to the definitions included) and provides useful guideline for the learning.