Operas and musicals presented in concert version are performances with limited or no staging, sets and costumes. The singers and the orchestra are usually together on the stage or concert platform rather than placing the orchestra in an orchestra pit. Often the chorus is placed towards the rear or sides of the stage, with the principal singers at the front of the stage, in front of the orchestra. As compared with a fully staged theatre production, the lower cost of producing a concert version and the reduced rehearsal time required have made this style of theatre performance increasingly popular in the 21st century, although the practice dates back to some of the earliest operas of the 17th century.