What is Computer Telephony Integration?

Legal Definition
Computer telephony integration, also called computer–telephone integration or CTI, is a common name for any technology that allows interactions on a telephone and a computer to be integrated or coordinated. The term is predominantly used to describe desktop-based interaction for helping users be more efficient, though it can also refer to server-based functionality such as automatic call routing.
-- Wikipedia
Legal Definition
Software and hardware that like the computer and phone.