Music is an art form in which the medium is sound organized in time. Common elements of music are pitch (which governs melody and harmony), rhythm (and its associated concepts tempo, meter, and articulation), dynamics, and the sonic qualities of timbre and texture. The word derives from Greek μουσική (mousike), "(art) of the Muses".

Definition of music
Musical notations
Greek philosophers and ancient Indians defined music as tones ordered horizontally as melodies and vertically as harmonies. Music theory, within this realm, is studied with the presupposition that music is orderly and often pleasant to hear. However, in the 20th century, composers challenged the notion that music had to be pleasant by creating music that explored harsher, darker timbres. The existence of some modern-day music genres such as death metal and grindcore, which enjoy an extensive underground following, indicate that even the harshest sounds can be considered music if the listener is so inclined.
20th-century composer John Cage disagreed with the notion that music must consist of pleasant, discernible melodies. Instead, he argued that any sounds we can hear can be music, saying, for example, "There is no noise, only sound."According to musicologist Jean-Jacques Nattiez, "the border between music and noise is always culturally defined—which implies that, even within a single society, this border does not always pass through the same place; in short, there is rarely a consensus.… By all accounts there is no single and intercultural universal concept defining what music might be, except that it is 'sound through time'."
The creation, performance, significance, and even the definition of music vary according to culture and social context. Music ranges from strictly organized compositions (and their recreation in performance), through improvisational music to aleatoric forms. Music can be divided into genres and subgenres, although the dividing lines and relationships between music genres are often subtle, sometimes open to individual interpretation, and occasionally controversial. Within "the arts", music can be classified as a performing art, a fine art, or an auditory art form.

Education
Primary
The incorporation of music training from preschool to post secondary education is common in North America and Europe. Involvement in music is thought to teach basic skills such as concentration, counting, listening, and cooperation while also promoting understanding of language, improving the ability to recall information, and creating an environment more conducive to learning in other areas.In elementary schools, children often learn to play instruments such as the recorder, sing in small choirs, and learn about the history of Western art music. In secondary schools students may have the opportunity to perform some type of musical ensembles, such as choirs, marching bands, concert bands, jazz bands, or orchestras, and in some school systems, music classes may be available. Some students also take private music lessons with a teacher. Amateur musicians typically take lessons to learn musical rudiments and beginner- to intermediate-level musical techniques.
At the university level, students in most arts and humanities programs can receive credit for taking music courses, which typically take the form of an overview course on the history of music, or a music appreciation course that focuses on listening to music and learning about different musical styles. In addition, most North American and European universities have some type of musical ensembles that non-music students are able to participate in, such as choirs, marching bands, or orchestras. The study of Western art music is increasingly common outside of North America and Europe, such as the Indonesian Institute of the Arts in Yogyakarta, Indonesia, or the classical music programs that are available in Asian countries such as South Korea, Japan, and China. At the same time, Western universities and colleges are widening their curriculum to include music of non-Western cultures, such as the music of Africa or Bali (e.g. Gamelan music).

Academia
Musicology is the study of the subject of music. The earliest definitions defined three sub-disciplines: systematic musicology, historical musicology, and comparative musicology or ethnomusicology. In contemporary scholarship, one is more likely to encounter a division of the discipline into music theory, music history, and ethnomusicology. Research in musicology has often been enriched by cross-disciplinary work, for example in the field of psychoacoustics. The study of music of non-western cultures, and the cultural study of music, is called ethnomusicology.
Graduates of undergraduate music programs can go on to further study in music graduate programs. Graduate degrees include the Master of Music, the Master of Arts, the Doctor of Philosophy (PhD) (e.g., in musicology or music theory), and more recently, the Doctor of Musical Arts, or DMA. The Master of Music degree, which takes one to two years to complete, is typically awarded to students studying the performance of an instrument, education, voice or composition. The Master of Arts degree, which takes one to two years to complete and often requires a thesis, is typically awarded to students studying musicology, music history, or music theory. Undergraduate university degrees in music, including the Bachelor of Music, the Bachelor of Music Education, and the Bachelor of Arts (with a major in music) typically take three to five years to complete. These degrees provide students with a grounding in music theory and music history, and many students also study an instrument or learn singing technique as part of their program.
The PhD, which is required for students who want to work as university professors in musicology, music history, or music theory, takes three to five years of study after the Master's degree, during which time the student will complete advanced courses and undertake research for a dissertation. The DMAis a relatively new degree that was created to provide a credential for professional performers or composers that want to work as university professors in musical performance or composition. The DMA takes three to five years after a Master's degree, and includes advanced courses, projects, and performances. In Medieval times, the study of music was one of the Quadrivium of the seven Liberal Arts and considered vital to higher learning. Within the quantitative Quadrivium, music, or more accurately harmonics, was the study of rational proportions.
Zoomusicology is the study of the music of non-human animals, or the musical aspects of sounds produced by non-human animals. As George Herzog (1941) asked, "do animals have music?" François-Bernard Mâche's Musique, mythe, nature, ou les Dauphins d'Arion (1983), a study of "ornitho-musicology" using a technique of Nicolas Ruwet's Language, musique, poésie (1972) paradigmatic segmentation analysis, shows that bird songs are organised according to a repetition-transformation principle. Jean-Jacques Nattiez (1990), argues that "in the last analysis, it is a human being who decides what is and is not musical, even when the sound is not of human origin. If we acknowledge that sound is not organised and conceptualised (that is, made to form music) merely by its producer, but by the mind that perceives it, then music is uniquely human."
Music theory is the study of music, generally in a highly technical manner outside of other disciplines. More broadly it refers to any study of music, usually related in some form with compositional concerns, and may include mathematics, physics, and anthropology. What is most commonly taught in beginning music theory classes are guidelines to write in the style of the common practice period, or tonal music. Theory, even that which studies music of the common practice period, may take many other forms. Musical set theory is the application of mathematical set theory to music, first applied to atonal music. Speculative music theory, contrasted with analytic music theory, is devoted to the analysis and synthesis of music materials, for example tuning systems, generally as preparation for composition.