A PhD is the highest academic qualification in the Netherlands. It generally involves four years of original research on a specific topic. Students who have a Master's degree can apply for a position, and are selected on the quality of their (educational) background.
A regular PhD programme takes 4 years of independent research, supervised by a professor. The programme is concluded by a thesis (dissertation) and/or a series of articles in scientific journals. As PhD student you get the opportunity to contribute to the development of knowledge in your subject.
There are several ways to obtain a PhD. Most PhD candidates in the Netherlands are not students but employees of the university. The primary criterion for admission to a PhD programme is the quality of the candidate.