If you intend to stay in The Netherlands for more than three months (including EU/EEA nationals) you must register at the GBA within five days of arrival. The GBA (Gemeentelijke basisadministratie personsgegevens) is the personal records database of the municipal authority. Registration is free of charge and they print-out a proof of residency and rights. You need to have a valid passport for your period of stay, birth certificate and a rental contract in your name. As you register you will get your BSN number (burgerservice number) which is necessary when you work in The Netherlands. You will also need a BSN number in order to  open a bank account.  The BSN number has officially replaced the old sofi (social/fiscal) number. However, if you intend to live and work in The Netherlands for a shorter period than three months you can still apply for a sofi number via the tax office instead of a BSN number.

If you move residence, you need to visit the municipality to inform them about the changes, if you decided to move away from The Netherlands you should inform the GBA as well.