How to Succeed in the Software Business While Giving Away the Source Code: The AdaCore Experience

Open source software or, more accurately, freely licensed open source software (FLOSS) at first appears to present a dilemma when adopted as part of a business model. If users are allowed to access, modify, and/or redistribute the source code, how does a company protect its intellectual property and, more fundamentally, sell something that can be easily and legally reproduced?