Choral music refers to music which is sung by a choir. Each musical part is sung by two or more voices. 

The size of a choir varies; it can be as few as a dozen singers or as large as to be able to sing Gustav Mahler's Symphony No. 8 in E Flat Major, also known as Symphony of a Thousand.

The suite is a type of instrumental dance music that emerged during the Renaissance and was further developed during the Baroque Period.

It consists of several movements or short pieces in the same key and functions as dance music or dinner music during social gatherings.

The fugue is a type of polyphonic composition or compositional technique based on a principal theme (subject) and melodic lines (counterpoint) that imitate the principal theme. 

The fugue is believed to have developed from the canon which appeared during the 13th century.

Also known as church music, it is music performed during worship or a religious rite. It evolved from the music performed in Jewish synagogues.

 In its early form, singers were accompanied by an organ, then by the 12th-century liturgical music adapted a polyphonic style.

Motet emerged in Paris around the year 1200. It is a type of polyphonic vocal music which uses rhythm patterns. 

Early motets were both sacred and secular; touching on subjects like love, politics and religion. It flourished until the 1700s and today is still being used by the Catholic Church.

An opera is generally referred to as a stage presentation or work that combines music, costumes, and scenery to tell a story. Most operas are sung, with few or no spoken lines. 

The word "opera" is actually a shortened word for the term "opera in musica".

An oratorio is an extended composition for vocal soloists, chorus and orchestra; the narrative text is usually based on scripture or biblical stories but is non-liturgical.

Although the oratorio is often about sacred subjects, it may also deal with semi-sacred subjects.

It is a form of medieval church music that involves chanting; it emerged around 100 C.E. 

Plainchant does not use any instrumental accompaniment. Instead, it uses words that are sung. It was the only type of music allowed in Christian churches early on.

Polyphony is a characteristic of Western music.

It began when singers started improvising with parallel melodies, with emphasis on fourth (ex. C to F) and fifth (ex. C to G) intervals. This marked the start of polyphony wherein several musical lines were combined.

As singers continued experimenting with melodies, polyphony became more elaborate and complex.

A round is a vocal piece wherein different voices sing the same melody, at the same pitch, but the lines are successively sung.

An early example of a round is Sumer is icumen in, a piece that is also an example of a six-voice polyphony. The children's song Row, Row, Row Your Boat is another example of a round.

A symphony often has 3 to 4 movements. The beginning is moderately fast, the next section is slow followed by a minuet, and then a very fast conclusion.

Symphonies had its roots from Baroque sinfonias, but composers like Haydn (known as "The Father of the Symphony") and Beethoven (whose popular work includes the "Ninth Symphony") further developed and influenced this music form.