1. Hydrocarbons are organic compounds made of only carbon and hydrogen. They can be classified as saturated or unsaturated depending on the bonding between carbon atoms. 2. Saturated hydrocarbons contain only single bonds between carbons, like alkanes. Unsaturated hydrocarbons contain at least one double bond between carbons, like alkenes. 3. Hydrocarbons undergo complete or incomplete combustion with oxygen, producing carbon dioxide, water, and sometimes carbon monoxide or soot depending on the availability of oxygen.