Prostitution or sex work means offering sex in exchange for money or other advantages. There is a difference between sex workers who voluntarily choose to engage in sex work and victims of human trafficking who are forced into prostitution. Consequently, sex work is not punishable, but forcing someone to engage in sex work is.

Sex work is legal in Belgium provided that both the sex worker and client are older than 18 and that the sex worker acts of his/her free will and with consent. They are doing nothing that is forbidden by law.  

Forced prostitution and human trafficking are forbidden by law. Sexual exploitation of minors in prostitution is also forbidden. Teenage pimps who seduce girls and start a false relationship with them in order to then force them into prostitution can also be punished.