Halal simply means permitted or lawful. So when we are talking about halal foods it means any foods that are allowed to be eaten according to Islamic Sharia law.
This means that for any food to be considered halal it must comply with the religious ritual and observance of Sharia law.
This means that food has been subjected to approved certification systems which guarantee to consumers that nothing in the food has any forbidden components. Halal certificates are issued, for a fee, by a certifying body.
Halal Certificate: Download PDF