It is both asset and currency like the other said but you cant' just use bitcoin for everyday usage frequently as the price goes up and down, it is not advisable to use it as a common currency like USD and other fiat ones, It is great to use it as an asset and investment as the btc continues to grow everyday. you will gain such profit if you store enough coins, but don't get me wrong it is still currency not just stable to use it for now.