Maybe it sounds a bit weird, but as an experience traveler I know that you every now and then need this kind of information in advance: electricity in the Netherlands is 230 Volts, alternating at 50 cycles per second. If you travel to the Netherlands with a device that does not accept 230 Volts at 50 Hertz, you will need a voltage converter.
There are three main types of voltage converter. Resistor-network converters will usually be advertised as supporting something like 50-1600 Watts. They are light-weight and support high-wattage electrical appliances like hair dryers and irons. However, they can only be used for short periods of time and are not ideal for digital devices. Some companies sell combination converters that include both a resistor network and a transformer in the same package. This kind of converter will usually come with a switch that switches between the two modes. If you absolutely need both types of converter, then this is the type to buy.
Outlets in the Netherlands generally accept 1 type of plug: Two round pins (see the picture). If your appliances plug has a different shape, you may need a plug adapter. Depending on how much you plan to travel in the future, it may be worthwhile to get a combination voltage converter and plug adapter.
The electrical current in the Netherlands is 220 volts, 50 cycles alternating current (AC); wall outlets take Continental-type plugs, with two round prongs..