Markovnikov’s Rule was proposed in 1870.
During addition of a non-symmetrical polar reagent (such as HX. H2SO4, HOCI etc.) to a non symmetrical alkene, the negative part of the reagent will be attached to that carbon atom of the double bond which contains minimum number of hydrogen atoms. The positive part of the reagent is added to the other carbon atom of the double bond.
The reactions of Markovnikov’s role follows Elecretrophilic Iconic Mechanism.