A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste.

In bilaterally symmetrical animals, nervous tissue concentrate at the anterior region, forming structures responsible for information processing.

Through biological evolution, sense organs and feeding structures also concentrate into the anterior region; these collectively form the head.

Philosopher John Searle asserts his identist beliefs, stating "the brain is the only thing in the human head".

Similarly, Dr. Henry Bennet-Clark has stated that the head encloses billions of "miniagents and microagents (with no single Boss)".

In some cases, the eyes may be seen as marks on the dorsal or located near or toward the head, two or three ocelli (single faceted organs).

[6] Antennae on the insect's head is found in the form of segmented attachments, in pairs, that are usually located between the eyes.

[9][10] In 2014, a transient larva tissue of the lancelet was found to be virtually indistinguishable from the neural crest-derived cartilage which forms the vertebrate skull, suggesting that persistence of this tissue and expansion into the entire headspace could be a viable evolutionary route to formation of the vertebrate head.

[13] Leonardo da Vinci, considered one of the world's greatest artists, drew sketches of human anatomy using grid structures.

[14] In this genre, using the technique of pen and ink, Leonardo created a sketch which is a "Study on the proportions of head and eyes" (pictured).