A single platform to download individual applications across multiple operating systems. What's not to love? Adobe Air (which stands for Adobe Integrated Runtime) is a sleek runtime platform that installs and runs an application on Windows, Mac, and Linux computers. You'll need it to download applications built using Air. Since developers need only make one version of the app for all three computing platforms, they can spend more quality time creating their product.
Or so the theory goes. As a runtime and delivery mechanism, Air won't determine how well the app fulfills its purpose, but programs built on Air do tend to look sleek and polished, like Web apps pulled down to the desktop. They also install quickly and seamlessly, as long as you've got the most recent version of Air running. If you don't, each app installation will prompt you.
Air has allowed developers to make hybrid applications, or desktop tools that can integrate with various Web services, while still allowing some offline functionality that Web browsers don't yet have. This includes things like taskbar and dock notifications. It continues to develop alongside advances to Adobe's other Web plug-ins. If you're looking at desktop applications based on Air, you should definitely give it a try.