Aliphatic compounds-
1.Can be saturated
 2.Joined by single bonds called Alkanes
 3. unsaturated, with double bonds called alkenes 
4.Triple bonds called alkynes.
 Besides hydrogen, other elements can be bound to the carbon chain, the most common being oxygen, nitrogen, sulphur, and chlorine.
Aliphatic compound is a chemical compound belonging to the organic class in which the atoms are not linked together to form a ring. One of the major structural groups of organic molecules, the aliphatic compounds include the alkanes, alkenes, and alkynes, and substances derived from them—actually or in principle—by replacing one or more hydrogen atoms by atoms of other elements or groups of atoms.