Carbon which have double bond or triple bond is called unsaturated compound

Hydrocarbons having double or triple covalent bond between carbon and carbon are called unsaturated hydrocarbons. Compounds of carbon and hydrogen are known as hydrocarbons.
Unsaturated found consist of alkene and alkyne and it has 2 and 3 bonds and the first member of alkene and alkyne are starting from Eth and alkene basic formula is CnH2n and alkyne is CnH2n- 2 where value of n start from 2 not 1