Opera music includes two categories: vocal music and instrumental music. Opera music is the instrumental part other than the vocal part in an opera, such as preludes, interludes, aria preludes, interlude endings, etc. In German opera, the human voice is sometimes regarded as an instrument rather than the lead singer. This part that uses the human voice as an instrument and performs in concert with the orchestra can also be understood as opera music.

Opera performances, like those of drama, rely on the typical elements of theater, such as backgrounds, costumes, and performances. Generally speaking, unlike other dramas, opera performances pay more attention to musical elements such as singing and the singer's traditional vocal skills.

Singers and choruses are often accompanied by a team of instrumentalists. Some operas only require a small band, while others require a complete orchestra. Some operas are interspersed with dance performances. For example, many French operas have a ballet performance.

Opera is regarded as part of the Western classical music tradition, so like classical music, it is not as popular as contemporary pop music, and modern musicals are regarded as modern versions of opera.