The aliphatic hydrocarbons are a broad class of hydrocarbons including alkanes, alkenes, and alkynes.  Some of these structures are straight chains, some are branched, and some are cyclical.

Aliphatic hydrocarbons can be divided into two main groups: saturated and unsaturated.

• Saturated hydrocarbons contain only carbon-carbon single covalent bonds with the maximum number of hydrogen atoms bound to each carbon.  The alkanes are saturated hydrocarbons.
  
  
• Unsaturated hydrocarbons contain carbon-carbon double or triple covalent bonds.  This group includes the alkenes and the alkynes.  These compounds have fewer hydrogen atoms than compounds with carbon-carbon single bonds.