New terminology

Alkanes are hydrocarbons where all carbons are joined by single bonds.

Alkanes are referred to as saturated because they have maximum number of single bonds at all of their atoms. 

Each carbon is involved in four bonds to other atoms and each hydrogen is involved in one bond to other atoms.

In saturated hydrocarbons like those below, there is the maximum number of hydrogens at every carbon.


The alkanes forms a homologous series
Each member of this series differs from the one before and the one after by a CH2.
For alkanes:  CH4, C2H6, C3H8, C4H10 and so on.

This can be used to derive a general molecular formula for alkanes which, when given the number of carbons allows one to predict the number of hydrogens.