Gammon is the name given to the meat from the hind legs of a pig that has been cured in the same way as bacon. The main difference between gammon and ham is that gammon will be sold raw and needs to be cooked; ham is sold cooked or dry-cured and ready for eating. Once gammon is cooked it can be called a ham and may be sold as a gammon ham.
More gammon recipes
Gammon joints are sold at various weights, with or without the bone, smoked or unsmoked. In the past, gammons needed soaking overnight in cold water to remove excess saltiness; nowadays this is generally unnecessary because of modern curing methods - check when buying as some more traditionally cured gammons may benefit from soaking. Gammon joints can be boiled or roasted and gammon steaks (cut thickly from the joint) are best grilled or pan-fried.