I just looked Physics graduate admission application guidelines on websites of various US and other International universities. There wasn't any mention of Extracurricular activities at all, unlike undergrad applications which use them as a crucial factor for admission decisions. Do they matter at all? Or should I just focus on grades and research during my undergraduate studies? Secondly, what about internships? I have looked up a lot of good organizations in my country and abroad where I think doing internships will prove to be very educational and constructive including the Pakistan Atomic Energy Commission and the Perimeter Institute in Canada and I plan to apply there. Will that help at all in my graduate application?