I had some questions about this in the past so I thought I'd sift through my PM's and find what I'd written up.
It wasn't very good. So here is an updated version:
Q: Why do the moderators / administrators use infractions?
A: To introduce the idea of 'demerits' or 'yellow and red cards', whichever you prefer, to standardize the moderation somewhat and to allow activities which are counter to the rules to be tracked by different mods across different forums. (note: Rules are available here for your review)
Q: I have gotten an infraction, now what?
A: Well first, please make sure you understand why. You should have gotten a PM along with the infraction which detailed why you received it. Maybe see the rules link above You can of course PM the moderator to find out why if you honestly don't know and can't figure it out and want to ensure that you don't get another one.
Q: Do infractions last forever?
A: No. They expire after 10 days. But the mods can see the history of infractions.
Hope that explains the process a little bit, if there is anything I missed I'm sure the other moderators will add it