I recently came across something when reading about transactions that I want to learn more about. A request is made, and a fee is then added, when someone wants to send some BTC to someone else. The sender can choose their own price or accept a preset amount. The recipient of transaction fees is? They appear to be independent of the incentive for finding a block, but as this becomes more expensive, will transaction fees be the only source of funding for BTC? as so, who will profit from them?