Markovnikov's rule

Markovnikov's rule states that, in chemical reactions found particulary in organic chemistry, when a a hydrogen halide reacts with the carbon-carbon double bond of an unsymmetrical alkene, giving an alkyl halide, the hydrogen adds to the carbon of the alkene functional group that has the greater number of hydrogen substituents, and the halogen adds to the carbon on the other end of the double bond which has a smaller number of hydrogen substituents.

The rule may be summed up by quoting that the rich get richer and the poor get poorer, in that a carbon rich in substituents will get more substituents and the carbon with more hydrogens attached will get the hydrogen in case of many different organic addition reactions.