Even though waves break everywhere along a coast, good surf spots are rare. A surf break that forms great surfable waves may easily become a coveted commodity, especially if the wave breaks there only rarely. If this break is near a large population center with many surfers, territorialism often arises. Regular surfers who live around a desirable surf break may often guard it jealously, hence the expression "locals only." The expression is common in beach towns, especially those that attract seasonal vacationers who live outside the area. Localism is expressed when surfers are involved in verbal or physical threats or abuse to deter people from surfing at certain spots. It is based in part on the belief that fewer people mean more waves per surfer.