The OV-chipkaart is the way you pay for public transport in the Netherlands. You can travel on all buses, trams and trains with a loaded OV-chipkaart. Not only with HTM, but also with all the other public transport companies in the Netherlands. The way it works is simple: make sure you always have enough credit (balance) or a travel product on your OV-chipkaart, then all you have to do is to check in and out.