The Netherlands are part of the so-called Schengen group, a group of European countries that apply the same rules for admittance. Between countries of the Schengen group, there exists no border controls anymore, and visa for one of the Schengen countries give also admittance for all other Schengen countries. Travellers from outside the Schengen group usually do need a visum, although for some countries only a valid passport which contains biometrical data is sufficient.
All relevant information concerning admittance, passports and visa can be found on the offical site of the Dutch government. On this site you will find also a list of the Schengen countries and a list of those countries for which only a valid passport without a visum is required.
Be aware of the fact that you are obliged to be able to identify yourself in the Netherlands, so also if you travel from one Schengen country to another, don’t forget to take your passport.