Easyride is a "pay as you go" system. But in stead of installing expensive card readers like they did in the Netherlands or London it is all done in software.
You set if up first. You need to create an account on sbb.ch (select "no customer number" so you don't get sidetracked in getting a Swiss Pass). You will need to enter a credit card, and it will be tested by placing a temporary hold on it.
Then you just check in by moving a big slider to the left before you start a trip. Then you just travel, getting on busses, trains etc... and at the end you move the slider to the right and the system checks you out, figures out what you did and charges you for the trip.