Is piano considered a percussion instruments?

Pianos can be considered a number of different instruments. It is a 'keyboard' instrument as it is played using a keyboard (I know its obvious!); a string instrument as the sound is made by strings, but also it is a percussion instrument because you play it by pressing keys. It's tuned percussion as it has different pitches (for example, a drum is not tuned percussion as it cannot play a tune, just a rhythm).