Finally, non-pirate peer-to-peer file-sharing systems exist. Weed, perhaps the best, has been designed to both encourage wide/easy distribution of music and provide artists with the money they're due, by having a file format that allows a downloaded song to be played three times for free and then requires payment for that song. It also gives prolific aficionados kickbacks: if someone else buys a song they downloaded from you, you get a percent of the proceeds. Most titles are about $1, but it varies--Weed says "The artist decides what to charge". According to Wired, Weed only keeps 15% of the song price; however, they don't need to make much money per file, because they outsource their infrastructure to their users. Such outsourcing to the end-user is an important Worldchanging trend that we'll see more of in the future. Other legally-paying P2P networks are AltNet and soon-to-be-launched Peer Impact.