Poissy is a commune situated in the Yvelines department within the Île-de-France region of north-central France. Located in the western suburbs of Paris, it sits approximately 23.8 km (14.8 mi) from the city center.
The town has a population of about 41,000 inhabitants, who are known as Pisciacais in French. It currently ranks as the fifth most populated commune in the Yvelines department.