The start of a relationship
Once approval has been obtained to award the contract the contract documents have to be prepared and checked by both parties.
The signing of the contract can be performed by each party separately or by means of a signing ceremony.
In some situations a section or sections of the contract document are not yet fully ready and if the acitivities need to start then a Letter of Intent, Notice to Proceed or other form could be used.
Sometimes a number of negotiation rounds are conducted with the prefered bidder prior to signing the contract.