[hazebooth]

As much as I like private trackers, very few use the ratio-less model to protect against serial leechers.

Typically on a tracker you’re given a currency (although not as sound as some e-coins) and can use that to influence your upload or download statistics, which in turn affect your ratio. Some trackers might employ rules where your user class has to have a certain ratio, or else you’ll lose privileges like certain forums or even the ability to download at all. (The trackers are private and can control which peers you can see)