Singing is the act of producing musical sounds with the voice, and augments regular speech by the use of both tonality and rhythm. A person who sings is called a singer or vocalist. Singers perform music known as songs that can either be sung a cappella (without accompaniment) or accompanied by musicians and instruments ranging from a single instrumentalist to a full symphony orchestra or big band. Singing is often done in a group of other musicians, such as in a choir of singers with different voice ranges, or in an ensemble with instrumentalists, such as a rock group or baroque ensemble.

Singing can be informal and done for pleasure; for example, singing in the shower or karaoke; or it can be very formal, as in the case of singing during a religious ritual such as a Mass or professional singing performances done on stage or in a recording studio. Singing at a high amateur or professional level usually requires instruction, and regular practice. Professional singers usually build their careers around one specific musical genre, such as Classical or rock, they typically take voice training provided by a voice teacher or vocal coach throughout their career.