It's a new feature.
You get merit points when someone sends you some for one of your posts. Additionally, when someone sends you merit points, half of those points can be sent by you to other people.
Certain users are designated as "merit sources". They can create new merit out of nothing, up to a limited number per month (which differs per source). I will not be posting a definitive list of merit sources (so that people don't bug them too much), though you'll soon figure out who they are if you pay attention.
There is currently no such thing as a "demerit". I'm hoping that the positive merits alone will be fine. I could add demerits pretty easily later on if necessary, though.
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Topic: Merit & new rank requirements