Offal refers to the edible internal organs of a butchered animal. Many of these organs are relatively inexpensive and highly nutritious.
The main offal used for eating are:
tripe (the stomach lining of a cow or sheep)
oxtail (the tail of cattle)
head (for example, pig’s heads are used for brawn, calves’ heads are used for soup)
suet (hard white fat from around the kidneys of beef or mutton)
marrow (a soft fatty tissue in the inside of bones)
brains
liver
kidneys
heart
sweetbreads (culinary name for thymus or the pancreas)
tongue.