Question

what are the functional group and the types of functional groups

Answer 1

functional groups are the atom or group of atom which form the chemical properties of an organic compounds.
types are
alcohol
ketone
carboxylic acid
aldehyde
halogen
ester
ether

Answer 2

Atoms or group of atoms that decide chemical properties of substances is known as functional group .
For example
Alcohol group - ol suffix
Aldehyde group - al suffix
on this basis ethanol is different from ethane