The isomers which have the same bond connectivity but a different arrangement of groups or atoms in space are termed as stereoisomerism.
These are two further types of stereoisomers :
1.Geometrical isomerism.
2.Optical isomerism
Geometrical isomerism: The compounds having a similar molecular formula but different arrangements of atoms or groups in space around the double bond are called as geometrical isomers and the phenomena are called as geometrical isomerism. This arises due to restricted rotation of c-c bond.
Optical isomerism: Those compounds which have the same molecular formula and same physical and chemical properties but shows different behavior towards plane polarised light is called an optical isomer and the phenomena are called optical isomerism.
Stereoisomerism is known as space isomerism.
Regards