There’s a lot of debate about what Open Source means. The wide variety of licenses and business models labeled as Open Source makes it hard to come up with a definition that everyone can agree on. The sheer number of Open Source licenses adds to the confusion. Popular licenses include: GPL, Creative Commons, BSD, Apache, Mozilla, MySQL, Sun’s CDDL. OpenSource.org list 58 different ‘approved’ Open Source licenses which meet the Open Source Initiative’s 10 point Open Source definition.Of all Open Source licenses, the BSD license is the simplest and most permissive. BSD software can be taken and embedded with software using a different type of license, and even resold as part of a commercial product.EnterpriseDB, for example, has built a successful commercial software business by building proprietary extensions on top of the BSD-licensed PostgreSQL database to create a low-cost clone of the Oracle RDBMS.If EnterpriseDB software extensions are not licensed as Open Source, how can the company claim to be an Open Source company? Consider what EnterpriseDB has given back to the community. EnterpriseDB is the single largest software contributor to the PostgreSQL project.Open Source as a movement dates back to 1998 after Netscape made their browser software available under the name of Mozilla. But there are different flavors of Open Source. Just because the source code is available, the code need not be licensed to allow it to be modified or redistributed. To distinguish Open Source projects that permit source code to be modified and redistributed, the term FOSS (Free Open-Source Software) has been coined.Many companies now experiment with hybrid licensing business models. MySQL provides four different licenses for gaining access to the MySQL code base. It’s not uncommon now for a company to provide an unsupported Open Source community-centric version of their software and also a for-fee commercially licensed version that provides support.