What is falsetto?

Good question. The ability to sing higher than your normal pitch by flipping to falsetto by using just a small portion of your vocal chords is what you're talking about. Some people cannot do it at all. It is almost an effeminate way to sing, and it yields brilliant results. Falsetto is called your "head voice." The other voice is your "chest voice." Paul McCartney uses a lot of falsetto especially in his song "Every Night," where the refrain is just a high pretty melody! It's on McCartney. You sort of leave out your bass and diaphragm for a moment and and sing from the top of your mouth and throat; your lips are almost closed like whistling.

Another master of the falsetto is Frankie Valli of The Four Seasons.