Site plan control is a form of development control provided to municipalities by Ontario's Planning Act. No one can undertake any development which is subject to site plan control unless the City has reviewed and approved certain plans. Once the plans are approved, a site plan agreement is generally executed. This agreement contractually binds the owner to develop and maintain a site in accordance with the approved plans and the terms of the agreement.
Source
http://www.oshawa.ca/mun_res/dev_appr/siteplan1.asp