TAU proposes a fast and secure currency without inflation. Users grow and secure the network by doing common behavior - transactions. With the innovation of "Proof-of-Transaction", mining clubs with transaction history are incentivated by generating blocks and reward to users. No advantage is for concentrating wealth and hardware as in POS and POW. Low barrier for commoners to get coins and mining is fairness. Proof-of-Transaction (POT) is an experimental consensus algorithm to determine which mining club will generate the next block, the more transaction history weight in the club, the high probability to get new block.