Bird beaks are multifunctional and can be used for feeding, grooming, building and fighting. The beak is also an indication of the type of food the bird consumes.
Here are some examples:
Chickens ... ... Strong, short and pointed beaks to pick upfood from the ground
Ducks ... ... Fringed to strain out the mud and water from their food.
Finches ... ... Conical beaks to be able to open up seeds.
Herons ... ... Long and sharp in order to spear the fish from the water.
Hummingbirds ... ... Long, needle-like beaks for gathering nectar from within a flower.
Toucans / Hornbills ... Large and swollen beaks to use with soft, pulpy fruit.