Construction bidding involves receiving proposals by the contractors to carry out a project at a certain cost and a certain time. Typically, it starts when the project owner posts a tender or a request of proposals (RFP). Contract then will evaluate the project needs, determine the costs and bid. Bids pitched by the contractors are then considered on price, experience and capability before the contract is awarded to the owner. The bidding may be either open (public) or selective (by invitation). Knowledge on how to come up with a competitive bid is essential in winning projects.