Are you planning to stay in the Netherlands for four months or more? You will need to register at the town hall in the municipality where you are living.
When you register with the municipality, you will receive a BSN (burgerservicenummer). This is a unique registration number that facilitates interaction with the Dutch authorities. You will need this number to start a job, open a bank account, do your taxes, apply for benefits etc.
For your online administration and to deal with certain agencies and bodies, such as the Belastingdienst (Dutch tax office) and the Dutch police, you will also need a DigiD (short for Digital Identification).
Note that when it comes to identification, your driving licence might not always be sufficient.