There are various ways of finding a doctoral position, with or without an employment contract.
Many PhD candidates are employed by the University as doctoral researchers with a view to completing a doctoral programme. Consult the list of vacancies for available doctoral positions.
It is also possible to obtain a doctorate without being employed by the UvA. Contract PhD candidates are those who have concluded an agreement with the UvA or a third party with a view to obtaining a doctorate. They may be funded by, or given time to pursue their studies by, an employer. Or they may receive a scholarship from the University or from another organisation. In both cases, they themselves are responsible for finding a supervisor.
It is also possible to obtain a doctorate from the UvA as an external PhD candidate. In this case, candidates do not enter into an agreement with a third party and do not receive a salary, but sometimes receive some material and/or financial support.
For specific doctoral programmes, consult the website of the relevant research institute or Graduate School.