European music is largely distinguished from many other non-European and popular musical forms by its system of staff notation, in use since about the 16th century. Western staff notation is used by composers to prescribe to the performer the pitch, speed, meter, individual rhythms and exact execution of a piece of music. This leaves less room for practices such as improvisation and ad libitum ornamentation, that are frequently heard in non-European art music (compare Indian classical music and Japanese traditional music) and popular music.
Characteristics
Given the extremely broad variety of forms, styles, genres, and historical periods generally perceived as being described by the term "classical music," it is difficult to list characteristics that can be attributed to all works of that type. Vague descriptions are plentiful, such as describing classical music as anything that "lasts a long time," a statement made rather moot when one considers contemporary composers who are described as classical; or music that has certain instruments like violins, which are also found in other genres. However, there are characteristics that classical music contains that few or no other genres of music contain.
Instrumentation
The instruments used in most classical music were largely invented before the mid-19th century (often much earlier), and codified in the 18th and 19th centuries. They consist of the instruments found in an orchestra, together with a few other solo instruments (such as the piano, harpsichord, and organ).
Electric instruments such as the electric guitar appear occasionally in the classical music of the 20th and 21st centuries. Both classical and popular musicians have experimented in recent decades with electronic instruments such as the synthesizer, electric and digital techniques such as the use of sampled or computer-generated sounds, and the sounds of instruments from other cultures such as the gamelan.
None of the bass instruments existed until the Renaissance. In Medieval music, instruments are divided in two categories: loud instruments for use outdoors or in church, and quieter instruments for indoor use. Many instruments which are associated today with popular music used to have important roles in early classical music, such as bagpipes, vihuelas, hurdy-gurdies and some woodwind instruments. On the other hand, instruments such as the acoustic guitar, which used to be associated mainly with popular music, have gained prominence in classical music through the 19th and 20th centuries.
While equal temperament became gradually accepted as the dominant musical temperament during the 19th century, different historical temperaments are often used for music from earlier periods. For instance, music of the English Renaissance is often performed in mean tone temperament. Keyboards almost all share a common layout (often called the piano keyboard).
Form
Whereas the majority of popular styles lend themselves to the song form, classical music can also take on the form of the concerto, symphony, sonata, opera, dance music, suite, étude, symphonic poem, and others.
Classical composers often aspire to imbue their music with a very complex relationship between its affective (emotional) content and the intellectual means by which it is achieved. Many of the most esteemed works of classical music make use of musical development, the process by which a musical idea or motif is repeated in different contexts or in altered form. The sonata form and fugue employ rigorous forms of musical development.
Technical execution
Along with a desire for composers to attain high technical achievement in writing their music, performers of classical music are faced with similar goals of technical mastery, as demonstrated by the proportionately high amount of schooling and private study most successful classical musicians have had when compared to "popular" genre musicians, and the large number of secondary schools, including conservatories, dedicated to the study of classical music. The only other genre in the Western world with comparable secondary education opportunities is jazz.
Complexity
Performance of classical music repertoire often demands a significant level of technical mastery on the part of the musician; proficiency in sight-reading and ensemble playing, thorough understanding of tonal and harmonic principles, knowledge of performance practice, and a familiarity with the style/musical idiom inherent to a given period, composer or musical work are among the most essential of skills for the classically trained musician.
Works of classical repertoire often exhibit artistic complexity through the use of thematic development, phrasing, harmonization, modulation (change of key), texture, and, of course, musical form itself. Larger-scale compositional forms (such as that of the symphony, concerto, opera or oratorio, for example) usually represent a hierarchy of smaller units consisting of phrases, periods, sections, and movements. Musical analysis of a composition aims at achieving greater understanding of it, leading to more meaningful hearing and a greater appreciation of the composer's style.
Society
Often perceived as opulent or signifying some aspect of upper-level society, classical music has generally never been as popular with working-class society. However, the traditional perception that only upper-class society has access to and appreciation for classical music, or even that classical music represents the upper-class society, may not be true, given that many working classical musicians fall somewhere in the middle-class income range in the United States, and that classical concertgoers and CD buyers are not necessarily upper class. Even in the Classical era, Mozart's opere buffe such as Così fan tutte were popular with the general public.
Classical music regularly features in pop culture, forming background music for movies, television programs and advertisements. As a result most people in the Western World regularly and often unknowingly listen to classical music; thus, it can be argued that the relatively low levels of recorded music sales may not be a good indicator of its actual popularity. In more recent times the association of certain classical pieces with major events has led to brief upsurges in interest in particular classical genres. A good example of this was the choice of Nessun dorma from Giacomo Puccini's opera Turandot as the theme tune for the 1990 FIFA World Cup, which led to a noticeable increase in popular interest in opera and in particular in tenor arias, which led to the huge sellout concerts by The Three Tenors. Such events are often cited as helping to drive increases in the audiences at many classical concerts that have been observed in recent times.
