Being a backup vocalist provides harmonies and vocals that complement the line and song performed by the Lead Vocalist. Some of you may ask how to sing backup? Good vocal control is essential, a backup vocalist must not try to 'outsing' the lead vocalist unless they have been directed to do so for a particular passage or effect!!
While most sound engineers and producers will adjust vocal volumes in the mix, it is important for singers who have strong voices to remember to back off the microphone a bit when providing backing for lead vocalists whose voices may not be as powerful.