There are many methods of killing animals for food. Among them are stunning, shooting and slaughtering.
Islam only allows meat of animals that have been slaughtered, their throats slit and the main veins and air pipe severed. Recent research indicates that the Islamic method of slaughter is the most humane as well as most beneficial all round.
Islam encourages that the animal be relaxed as possible before the slaughter, e.g. not to expose it to the other animals being slaughtered for instance. Research shows this produces better quality meat and gives it longer shelf life.
The knife should be sharp to minimize the pain to the animal. By cutting the windpipe, gullet and two arteries there is a swift draining of blood. This purifies the meat by removing most of the blood which acts as a medium for disease-bearing micro organisms.
The sacrifice of animals is a practice of the Prophets:
Narated By Anas (radhiallahu anhu):
The Prophet used to offer as sacrifice two horned rams, black and white in colour, and used to put his foot on their sides and slaughter them with his own hands (on the occasion of Eid ul Adha). [Bukhari]
There is an excellent example for you in the Prophet of Allah [Al Qur’aan]