What is a free radical substitution reaction and what are the stages?

A free radical substitution involves the reaction between an alkane and a halogen to form a halogenoalkane.The first step is initiation; this is where UV light breaks the X-X halogen bond, via homolytic fission, to create halogen radicals.The second step is propogation; this is where the radical generated in the initiation step attacks the alkane molecule, generating an alkyl radical and the corresponding hydrogen halide. The alkyl radical then attacks a halogen molecule, to give the halogenoalkane product, and regenerate the halogen radical.The final step is termination; two radicals combine to form a stable molecule.