Patrols are the principle operating group in Boy Scouting. In a lot of ways, one can best imagine a patrol to be very similar to a Hogwart's House in the Harry Potter novels. When a boy joins the troop, he is selected into a patrol which is chosen to be a good "fit" for his interest and personality. Once in his patrol, he's got older friends ranging from the group just ahead of him all the way up to the more senior scouts in the patrol - his "prefects" the Patrol Leader and Assistant Patrol Leader.
A scout generally stays in his patrol for most of his time in the troop. His patrol offers him the home among a small group of dedicated adventurors within the larger troop. He'll have older boys in his patrol who will coach him and watch out for him in his early years, then gradually he'll gain independence until he is helping coach and lead younger boys in his patrol. And, like the Harry Potter houses, he can earn "points" for his patrol in various activities along the way.
New boys are "sorted" into patrols in a way that tries to keep them together with close cub scout friends, while at the same time trying to hook them up with older scouts of similar interests and personalities. Unlike Hogwarts, brothers are generally never assigned to the same patrol, but much like the Hogwarts Sorting Hat, individual boys' preferences are taken into account.