Classical music
The dates are generalizations, since the periods and eras overlap and the categories are somewhat arbitrary, to the point that some authorities reverse terminologies and refer to a common practice "era" comprising baroque, classical, and romantic "periods". For example, the use of counterpoint and fugue, which is considered characteristic of the Baroque era (or period), was continued by Haydn, who is classified as typical of the Classical era. Beethoven, who is often described as a founder of the Romantic era, and Brahms, who is classified as Romantic, also used counterpoint and fugue, but other characteristics of their music define their era.

Q: Some authorities reverse terminologies to refer to the common practice period as a what?
era