In music, a note head is the elliptical part of a note. Noteheads may be coloured completely black or white, indicating the note value (i.e., rhythmic duration). In a whole note, the note head is the only component of the note. Shorter note values attach a stem to the note head, and possibly beams or flags. The longer double whole note can be written with vertical lines surrounding it, two attached note heads, or a rectangular note head.^{[citation needed]}

Note heads ultimately derive from the neumes used to notate Gregorian chant. The punctum, seen at right, is the simplest of the shapes and most clearly anticipates the modern note head. When placed on a clef, the position of a note head indicated the relative frequency of a note. The development of different colors of note heads, and the use of it to indicate rhythmic values, was the use of white mensural notation, adopted around 1450.^{[citation needed]}

Franco of Cologne, ancient composer and music theorist, codified a system of rhythm notation. He explained this system in his work, Ars Cantus Mensurabilis, (which means “The Art of Measurable Music”) circa 1280. In this system, the relative duration of notes was indicated by the note shapes. The note heads were rectangles, squares, or diamonds depending on the note length. This system was expanded during the Ars Nova period.

In music, the term note has two primary meanings:

Notes are the "atoms" of much Western music: discretizations of musical phenomena that facilitate performance, comprehension, and analysis.

The term "note" can be used in both generic and specific senses: one might say either "the piece 'Happy Birthday to You' begins with two notes having the same pitch," or "the piece begins with two repetitions of the same note." In the former case, one uses "note" to refer to a specific musical event; in the latter, one uses the term to refer to a class of events sharing the same pitch.

Two notes with fundamental frequencies in a ratio of any power of two (e.g. half, twice, or four times) are perceived as very similar. Because of that, all notes with these kinds of relations can be grouped under the same pitch class. In traditional music theory pitch classes are represented by the first seven letters of the Latin alphabet (A, B, C, D, E, F and G) (some countries use other names as in the table below). The eighth note, or octave is given the same name as the first, but has double its frequency. The name octave is also used to indicate the span of notes having a frequency ratio of two. To differentiate two notes that have the same pitch class but fall into different octaves, the system of scientific pitch notation combines a letter name with an Arabic numeral designating a specific octave. For example, the now-standard tuning pitch for most Western music, 440 Hz, is named a′ or A4. There are two formal ways to define each note and octave, the Helmholtz system and the Scientific pitch notation.

In anatomy, the head of an animal is the rostral part (from anatomical position) that usually comprises the brain, eyes, ears, nose and mouth (all of which aid in various sensory functions, such as sight, hearing, smell, and taste). Some very simple animals may not have a head, but many bilaterally symmetric forms do. Heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nerve tissues 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, which collectively form the head.

In human anatomy, the head is the upper portion of the human body. It supports the face and is maintained by the skull, which itself encloses the brain. Humans have the largest head size relative to body size of any species.^{[citation needed]}