Trappes is a commune located in the Yvelines department within the Île-de-France region of northern France. It serves as a banlieue situated in the western outer suburbs of Paris, positioned approximately 26.7 km (16.6 mi) from the city center.
The commune is an integral part of the new town of Saint-Quentin-en-Yvelines. It functions as a residential and urban area within the broader metropolitan framework of the Paris region.