Alpha Testing
Alpha Testing is the testing of a new product in pre-release internally before testing it with outside users. Alpha testing is conducted in a controlled environment and is conducted at the developer's site by a customer.
Alpha releases are typically for internal circulation only and are passed among a select group of mock users — often just the team working on the project. These versions of a product are often the first working drafts of your project, and you can expect them to have problems or to be incomplete. beta releases, on the other hand, are sent to a wider but still select audience with the same caveat: this software may contain errors, bugs, and unknown alligators that slither out of the swamp at day's end to bite startled designers from behind. Because your product is now being shown and used outside the privacy of its birth nest, its reputation will begin to take form during beta phase. Thankfully though, beta-level bugs are typically less virulent than alpha bugs. [Multimedia: making it work By Tay Vaughan]
Also see:
Beta Testing