Adobe AIR is a cross-operating system designed to let developers combine HTML, Adobe Flash, Ajax and Flex technologies to create rich Internet applications. AIR is a runtime system that works on any computer regardless of the operating system installed.
A rich Internet application is a term coined by Adobe describing an application that combines web-based and desktop applications to provide an engaging experience. These are typically sites located on the Internet but provide the user with an interactive experience. Adobe AIR is designed to have these applications function on any computer by making development easier because they are typically difficult to program.