Uninterruptible Power Supply. A system which allows computers
to keep running for a limited time during a power failure.
It gives you the chance to save data before your system
Uniform resource locator is the address of a file accessible
on the Internet, such as a website address. The unique
identification of a web site or web resource, such as
Universal Serial Bus. A standard port that enables you
to connect external devices
USM stands for Ultra Silent Motor, this simply means that
the lens will focus more quietly than a non-USM lens.