Ham is a leg of pork cured in one of several ways. Traditional salt based cures left high levels of salt in the meat and it is this that was removed by soaking. Too much salt obviously adversely effects the flavour of the meat. Some cured hams such as the air dried meats typical of Spain and Italy are eaten raw. Thinly sliced Parma ham is one such example. These air dried ham are quite salty in flavout but require no treatment before eating raw or adding to cooked dishes. Modern treatment methods are said to reduce the need for soaking but most recipes insist that soaking be part of the process. Usually the ham is left overnight in cold water and one soaking is sufficient. Some fastidious cooks like to change the water several times during soaking. If in doubt ask your meat supplier as they will usually offer the best advice.