Generally, a song is a musical composition that has lyrics and a tune. It can be for a solo singer, duet, or a trio. It can also be accompanied by a variety of instruments, including the piano or guitar. Some songs are performed a cappella.
Most songs consist of three main parts: an intro, a pre-chorus, and a chorus. Each part serves a different function. The chorus is usually the catchiest part of the song. It contains the melody and lyrics that sum up the main idea of the song.
The pre-chorus, also known as the lift, is a short segment at the beginning of the song that builds anticipation and heightens the impact of the chorus. It usually includes a chord progression from the verse. It may also repeat the same lyric.
The chorus is the climax of the song. It is often the title of the song and usually contains the melody used throughout the song. It can also be the most memorable part of the song.
The bridge is a section of a song that introduces a different melody and provides a contrasting perspective on the main song idea. It also separates repeating choruses in the song. It may use a different chord progression or a different rhythm. It provides a break from the repetitive nature of many songs.
The outro is a surprise. It can be the conclusion of the song and may be a new part. It usually finishes with an instrumental part.