http://en.wikipedia.org/wiki/Butcher

A butcher is a person who may slaughter animals, dress their flesh, sell their meat or do any combination of these three tasks.[1] They may prepare standard cuts of meat, poultry, fish, and shellfish for sale in retail or wholesale food establishments. A butcher may be employed by supermarkets, grocery stores, butcher shops and fish markets, slaughter house, or may be self-employed.[2]

An ancient trade, whose duties may date back to the domestication of livestock, butchers formed guilds in England as far back as 1272.[3] Today, many jurisdictions offer trade certifications for butchers. Some areas expect a three-year apprenticeship followed by the option of becoming a master butcher.

Butchery is a traditional line of work. In the industrialized world, slaughterhouses use butchers to slaughter the animals, performing one or a few of the steps repeatedly as specialists on a semiautomated disassembly line. The steps include stunning (rendering the animal incapacitated), exsanguination (severing the carotid or brachial arteries to facilitate blood removal), skinning (removing the hide or pelt) or scalding and dehairing (pork), evisceration (removing the viscera) and splitting (dividing the carcass in half longitudinally).

After the carcasses are chilled (unless "hot-boned"), primary butchery consists of selecting carcasses, sides, or quarters from which primal cuts can be produced with the minimum of wastage; separating the primal cuts from the carcass; trimming primal cuts and preparing them for secondary butchery or sale; and storing cut meats. Secondary butchery involves boning and trimming primal cuts in preparation for sale. Historically, primary and secondary butchery were performed in the same establishment, but the advent of methods of preservation and low cost transportation has largely separated them.

In parts of the world, it is common for butchers to perform many or all of the butcher's duties. Where refrigeration is less common, these skills are required to sell the meat of slaughtered animals.