The Open Source Initiative: A 30-Second Primer
What is open source?
Open source is a software licensing model. Unlike proprietary license models, which maintain the secrecy of source code, open source models grant immediate source code access. For this reason, it is often referred to as “free” software. However, the open source model does not advocate no-charge software. “Free” refers to the mandate that source code be disclosed in connection with distributed software. There are two types of open source license models - copyleft and non-copyleft models. Copyleft models ensure that acquired source code remains free for copying and modification by downstream users. Non-copyleft software places acquired source code closer to the public domain, thereby allowing incorporation into proprietary software by downstream users.
Copyleft software is distributed under one of several public licenses, the most prominent of which are the GNU General Public License (commonly referred to as the "GPL"),1 the GNU Lesser General Public License (commonly referred to as the "LGPL"),2 and the Mozilla Public License (commonly referred to as the MPL).3 Although each license contains slightly different terms, the core tenants of the copyleft model extend to each.
Non-copyleft software is most commonly distributed under the Berkeley Software Distribution license (commonly referred to as the "BSD"),4 the Massachusetts Institute of Technology License (commonly referred to as the "MIT"),5 and the FreeBSD license.6 These licenses include fewer restrictions than copyleft licenses.
What pitfalls should I investigate before adopting copyleft software?
Copyleft software is not in the public domain, and licensees cannot make unrestricted use. A copyleft licensee must abide by the terms of the governing open source license. Each copyleft license contains the same core terms, and by obtaining open source code, a licensee agrees to these terms. For instance, copyleft licenses include a "give-back" provision and a "no warranty" provision.
Any modifications and/or derivative works of copyleft code must be released under the governing copyleft license. The licensee has the obligation to: 1) distribute all underlying source code with the software; and 2) license all copies of the software only under the governing copyleft license, thereby allowing downstream users freedom to copy and modify licensee's software.
Accordingly, Licensees must be careful not to incorporate copyleft code into software it intends to keep proprietary or confidential. When open source code is incorporated into otherwise proprietary software, it is possible that some proprietary portions also become "open" and must be distributed under the governing copyleft license. Each time a licensor redistributes a copy of the software the recipient automatically receives a license from the original licensor to copy, distribute, or modify the software subject to these terms and conditions. This significant limitation ensures that open source software will never become proprietary.
Both copyleft and non-copyleft open source software are expressly exempt from any warranties of fitness. Licenses include general provisions excusing software creators from indemnifying against faulty software. However, licenses do allow specific authors to provide individual warranties where separately drafted.
What if I do not want to make modified copies of open source software available for free distribution and/or modification?
Non-copyleft open source licenses place relatively few restrictions on licensees. These licenses allow free copying, modification, and distribution provided licensees include certain copyright, advertising, and warranty notices. Importantly, distribution of modified non-copyleft software usually need not include source code access. Moreover, non-copyleft licensees need not "give-back" their modifications under the governing license. Accordingly, licensees can choose wither to distribute modified software under a copyleft, non-copyleft, or strictly proprietary model. This model better suits companies looking to keep their end product largely proprietary.
What are the benefits of incorporating open source software into a company's business model?
Open source advocates suggest that open source software is a superior product because multiple contributors allow software to evolve quickly. Advocates believe that the open source model creates more reliable software because code is exposed to public scrutiny, with problems being found and fixed. Some software entrepreneurs have experienced increased development speed, lower overhead, and a broader market by incorporating open source software into their business model.
Where can I learn more about the open source licensing model?
Due to significant differences between various open source licensing models, a company must carefully research which model best suits its needs. The Open Source Initiative provides up-to-date information on open source licensing models on its website located at http://www.opensource.org/. Before incorporating any open source model, a company should contact an attorney to receive detailed information about the possible benefits and detriments of adopting an open source model.
1To read the GPL see http://www.gnu.org/licenses/gpl.txt
2To read the LGPL see http://www.gnu.org/copyleft/lesser.txt
3To read the MPL see http://www.mozilla.org/MPL/MPL-1.1.txt
4To read the BSD see http://www.opensource.org/licenses/bsd-license.php
5To read the MIT see http://www.opensource.org/licenses/mit-license.html
6To read the Free BSD license see http://www.freebsd.org/copyright/freebsd-license.html