How is Salat al-Istikhara performed and what is its specific supplication (dua)?

The Istikhara prayer, as taught by the Messenger of Allah, peace and blessings be upon him, consists of two rak'ahs other than the obligatory prayer. Then the worshiper recites the Istikhara supplication, which begins with, "O Allah, I seek Your guidance by Your knowledge and Your power by Your might..." and asks Allah to decree what is good for him, make it easy for him, and bless him in it, or to avert evil from him and make him content with what He has decreed for him. Scholars have mentioned that the prayer before the supplication is to knock on the door of Allah, and that the supplication is made after finishing the prayer. Specifying the matter in the supplication is done either by verbalizing it or by bringing it to mind in the heart.