World of Warcraft is filled with food and drink. Although players are not required to eat or drink, they may receive benefits by keeping their characters full!

Food - Food regenerates health over time. The eating process or "buff" can be interrupted (canceled) if you are attacked or move. So don't use food unless your character is unlikely to be attacked.

Drinks - Drinks regenerate mana over time. Like food, the drinking process is a buff that can be interrupted if you are attacked. You must remain still while drinking (under the mana regeneration effect), or the "buff" will be canceled.

Information
More powerful food/drinks require higher player level limits; they will heal or regenerate more mana/health within a shorter amount of time too.