Classical music is a broad term that usually refers to mainstream music produced in, or rooted in the traditions of Western liturgical and secular music, encompassing a broad period from roughly the 9th century to present times. The central norms of this tradition became codified between 1550 and 1900, which is known as the common practice period.

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.

The public taste for and appreciation of formal music of this type waned in the late 1900s in the United States and United Kingdom in particular. Certainly this period has seen classical music falling well behind the immense commercial success of popular music, in the opinion of some, although the number of CDs sold is not indicative of the popularity of classical music.

The term 'classical music' did not appear until the early 19th century, in an attempt to 'canonize' the period from Johann Sebastian Bach to Beethoven as a golden age. The earliest reference to "classical music" recorded by the Oxford English Dictionary is from about 1836. Many writers feel that 'classical' is an inappropriate term for mainstream and avant-garde music written since the latter part of the 19th century, hence the common usage of apostrophes as a short-hand for 'so-called'.

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 bluegrass music, Broadway music, and other genres; or "relaxing" or "background" music for affluent people, descriptions which are probably only accurate when describing court music from the Baroque and Classical periods; indeed, many people do not find modern or avant-garde composers and works such as Threnody to the Victims of Hiroshima by Krzysztof Penderecki or Black Angels by George Crumb to be very relaxing or "snobby."

However, there are characteristics that classical music contains that generally few or no other genres of music contain.