Introduction to Domesticated Birds.

The chicken is a domesticated form of the red junglefowl. It is one of the most common and widespread domesticated animals in the world, raised primarily for its meat and eggs. As of 2003, there were over 26.5 billion chickens worldwide.
Chickens are medium-sized birds with round bodies, small heads, beaks, and wings. Their wings are short and they cannot fly very far. Male chickens are called roosters and female chickens are called hens. Both have a hanging skin (wattle) around their necks and a fleshy part (comb) on the top of their heads, which is usually larger in the case of roosters.

Chickens are social animals and live in flocks. There is a pecking order among them, with the dominant chicken getting the best food and roosting areas. They are omnivorous, meaning they eat both plants and animals, such as seeds, grains, fruits, and insects.

Specialist breeds such as broilers (for meat) and layers (for eggs) have been developed to increase productivity. A layer hen can lay more than 300 eggs a year. The economic importance of chickens is a central component of livestock farming worldwide.