A hydrocarbon is a compound which only contains carbon and hydrogen atoms as constituent elements. 
An alkane is a saturated hydrocarbon. Saturated means that is has no double bonds and has the maximum number of hydrogen atoms. All bonds present in an alkane are single bonds. 

General formula of alkanes: CnH₂n₊₂
If (n = 3), the compound would be:
C₃H₂₍₃₎₊₂ = C₃H₈

Every alkane’s name ends in ‘-ane’.

An alkane’s prefix always changes according the number of carbon atoms present in the compound. 

Some common alkanes:

Name of the alkaneNo. of Carbon atomsFormula
Methane1CH₄
Ethane2C₂H₆
Propane3C₃H₈
Butane4C₄H₁₀
Pentane5C₅H₁₂
Hexane6C₆H₁₄
Heptane7C₇H₁₆
Octane8C₈H₁₈
Nonane9C₉H₂₀
Decane10C₁₀H₂₂