P4P, or proactive network provider participation for P2P, is a method for internet service providers (ISPs) and peer-to-peer (P2P) software to optimize peer-to-peer connections. P4P proponents say that it can save an ISP significant costs, and that using local connections also speeds up download times for P2P downloaders by 45%,^[1] critics say that this will favor downloaders on some ISPs but come at the expense of others.