We study the existence of homoclinic points for hyperbolic periodic points for area preserving diffeomorphisms.We show that,on the two sphere and under some very mild conditions(no saddle connections),homoclinic points always exist.This can also be extended to other surfaces with some additional conditions.This result is motivated by the classical billiard and geodesic flow problems where there is no local perturbations,hence the existence of homoclinic points cant be achieved by local perturbations as has been done for generic surface diffeomorphisms.The main technique is the prime end compactifications.We will also discuss some other results related to homoclinic points.