There are many frequencies available in the world. Currently, most American musicians use the standard pitch (A=440Hz) for the tuning, but that does not apply to everyone in the world especially other than Rock/Commercial music, I believe.
Many classical orchestras tune higher like 442Hz to 445Hz, and guys like John Lennon & Paul McCartney have tuned their instruments to C5=528Hz (A=444Hz) in some of their songs (Paul started recording songs in 444Hz/528Hz after 1999).