Simply put it is the tail from Beef Cattle. Back in the day, Oxtail came from the tail of an “Ox” i.e., a male, farm steer, but it’s now sourced from cattle of any sex. A typical Oxtail will weigh around 2-3kg and is a combination of the tail bone, surrounding meat, and a nice fat layer.
Each portion will be approximately 2” long which is an ideal size for cooking, but also an ideal size to maximise the release of the bone marrow, fats, and gelatinous collagen. It's is luscious and rich meat.