An NS group ticket is a way of traveling cheaply by train. This ticket allows a group of between 4-10 persons to travel to or from any destination in the Netherlands. Passengers who want to use a Group Ticket will from now on have to travel together in the train, as opposed to the old group return ticket that made fraudulent behavior possible and was therefore changed. The new main rule is that a fellow passenger must always travel together with the main ticket holder, however, the fellow passengers can get on at a later station on the same route. The Group Ticket is for a single journey, but the group can buy a ticket for the return journey along with their outward journey. The return can also be for a later date.
You must buy the ticket online. The price is very cheap, compared to a single ticket; it goes for 7.50€ per person when traveling in 4. With an additional 1.50€ per person you can increase the amount of travelers on the ticket up to 10. Important to note is that the Group Ticket only lets you travel at off-peak hours. On Monday to Friday, that means before 06:30, between 09:00 and 16:00 and after 18:30. At weekends, it is all day from 18:30 on Friday evening until 06:30 on Monday morning.