What is the Markovnikov's addition?
From the mechanism I know, it helps in figuring out the products of electrophilic addition.
Electrophilic addition occurs when an alkene is added with a HX, where X is a halide.
So in a carbon chain, preferably propene, the double bond will first induce a +ve charge on to the hydrogen from HX. Hence X now has a -ve charge.
So the double bond breaks and the hydrogen and X halide bond to the carbon chain.
Markovnikov's rule helps here by explaining where the H+ and X- ion fix themselves and hence stating the major products of the reactions.
During the formation of the intermediate, there is a carbocation. Depending on the stability of this carbocation, the position of the X- halide will vary. Hence resulting in either eg. 1-bromopropane or 2-bromopropane.