Halogenation is an addition reaction where halogen (Cl2 and Br2) to an alkene or alkadiene.
Halogenation forms as a product vicinal halides, that is, two neighboring halogens.
This reaction is done by adding HX to the alkenes.
HX, where X is halogen.
Examples: HCl, HBr
In some cases we get two products. The "theoretically" expected should follow the Markovnikov Rule.
Markovnikov Rule - "In the addition reactions, hydrogen is added to the more hydrogenated double bond carbon".
However, we must be aware of the reactions where peroxide is present, because in these cases we use the rule Anti-Markovnikov, which is the inverse of Markovnikov.
Anti-Markovnikov example in case of addition of hydrogen bromide: