The piano is an acoustic, stringed musical instrument invented in Italy by Bartolomeo Cristofori     around the year 1700,in which the  strings are struck  by hammers. It is played using a keyboard, which is a row of keys (small levers) that the performer presses  down   or strikes with the fingers and thumbs of both hands to cause the hammers to strike the strings. The word  piano is a shortened form of pianoforte,  the Italian term for the early 1700s versions of the instrument, which in turn derives from  gravicembalo col  piano  eforte and  fortepiano.The Italian  musical  terms piano  and forte  indicate “soft”  and “loud” respectively, in this context referring to  the  variations in  volume (i.e., loudness)  produced   in  response to  a   pianist’s  touch  or  pressure  on the keys: the greater the velocity of a key press, the greater the force of  the hammer hitting  the  strings,  and  the louder the sound of the note produced  and the stronger the attack. The first fortepianos in  the 1700s  had  a quieter sound   and smaller dynamic range.

An acoustic piano usually has a protective wooden case  surrounding   the  soundboard and  metal strings,  which are  strung under  great   tension ona heavy metal frame. Pressing one or more keys on the piano’s keyboard causes a padded hammer to strike the   strings. The hammer rebounds from the strings, and the strings continue to vibrate at their resonant frequency. These vibrations are transmitted through a bridge to a soundboard that amplifies by more efficiently coupling the acoustic energy to the air.