You do not have to build a website or pay for additional hosting services the moment you register a domain name. The moment you register your domain name, registrars associate a placeholder website to it with little content. The amount and type of content depends on the registrar you’ve chosen.
This is called domain parking.
Of course, to actually make a use of your domain and build a website, you need to choose a hosting service that will support your needs. In case you want to create a website, you shouldn’t leave your domain parked for too long.
