The roots of western classical music lie in early Christian liturgical music, and its influences date even further back to the Ancient Greeks. Development of individual tones and scales was done by ancient Greeks such as Aristoxenus and the mathematician Pythagoras. Pythagoras created a tuning system and helped to codify musical notation. Ancient Greek instruments such as the aulos (a reed instrument) and the lyre (a stringed instrument similar to a small harp) eventually led to the modern day instruments of a classical orchestra. The antecedent to the early period was the era of ancient music from before the fall of the Roman Empire (476 AD). Very little music survives from this time, most of it from Ancient Greece.

The major time divisions of classical music are the early period (which includes Medieval (476 – 1400) and Renaissance (1400 – 1600)), the Common practice period (which includes Baroque (1600 – 1750); the Classical (1730 – 1820) and Romantic (1815 – 1910)) periods, and the modern and contemporary period which includes 20th century classical (1900 – 2000) and contemporary classical (1975 – current).

The dates are generalizations, since the periods overlapped and the categories are somewhat arbitrary. For example, the use of counterpoint and fugue, which is considered characteristic of the Baroque era, was continued by Mozart, who is generally classified as typical of the classical period. Beethoven, who is often described as a founder of the romantic period, and Brahms, who is classified as romantic, also used counterpoint and fugue, but it is other characteristics of their music that define their period.

The prefix neo is used to describe a 20th century or contemporary composition written in the style of an earlier period, such as classical, romantic, or modern. Stravinsky’s Pulcinella, for example, is a neoclassical composition because it is stylistically similar to works of the Classical period.

The Classical period, from about 1750 – 1820, established many of the norms of composition, presentation and style, and was when the piano became the predominant keyboard instrument. The basic forces required for an orchestra became somewhat standardized (although they would grow as the potential of a wider array of instruments was developed in the following centuries). Chamber music grew to include ensembles with as many as 8-10 performers for serenades. Opera continued to develop, with regional styles in Italy, France, and German-speaking lands predominating. The opera buffa, or comic opera, gained in popularity. The symphony came into its own as a musical form, and the concerto was developed as a vehicle for displays of virtuoso playing skill. Orchestras no longer required a harpsichord (which had been part of the traditional continuo in the Baroque style), and were often led by the lead violinist (whom we now call the concertmaster). More instruments too became integrated along with the music.

A culture’s music is influenced by all other aspects of that culture, including social and economic organization and experience, climate, and access to technology. The emotions and ideas that music expresses, the situations in which music is played and listened to, and the attitudes toward music players and composers all vary between regions and periods.  The Classical “Music history” is the distinct subfield of musicology and history which studies music (particularly western art music) from a chronological perspective.