How a Piano is Tuned
The piano is a C tuned instrument; like the string instruments and several other instruments. That means that all other instruments that are C tuned can play with each other and play the same notes and they will make the same tunes. Other instruments like the wind instruments and brass instruments they are turned to a different scale which means that when they play their notes what’s natural for their instrument to produce is actually going to be kind of crazy notes for a beginner to learn how to play. So as a result they change the names of their notes to be easy notes like C, D, E, F, and G rather than B flat, C, D flat, E flat; if they had to learn to play that way it would be very difficult. As a result when pianists have to play with other instruments they usually have to transpose to the piano so that they can play the same notes and pianists just need to play the notes that are in front of them.