An ocean ridge is an underwater mountain system which is the result of tectonic plate movement. Its formation involves two processes: ridge-push and slab pull. The former occurs when the growing bulk of the ridge pushes the rest of the tectonic plate away from the ridge. Oftentimes, they go towards a subduction zone. In this zone, the latter, which is the slab pull comes into effect. This is the weight of the tectonic plate subducted or pulled down below the overying plate tagging along the rest of the plate behind it.
They are generally located halfway between two continents.