Open source

Open source refers to something that can be modified because its design is publicly accessible. Originally the term was used in the context of computer software development, today it designates a set of values. Open source projects, products, or initiatives are those that embrace and celebrate open exchange, collaborative participation, transparency, meritocracy, and community development.

Open source hardware
Open source hardware is hardware whose design is made publicly available so that anyone can study, modify, distribute, make, and sell the design or hardware based on that design. The hardware's source, the design from which it is made, is available in the preferred format for making modifications to it. Ideally, open source hardware uses readily-available components and materials, standard processes, open infrastructure, unrestricted content, and open-source design tools to maximize the ability of individuals to make and use hardware. Open source hardware gives people the freedom to control their technology while sharing knowledge and encouraging commerce through the open exchange of designs.

Licenses
The most commonly used open hardware licenses are the Creative Commons Licenses and the GNU General Public License (GNU GPL). You must understand what your entitlements and responsibilities are, read and understand the terms of the licencing for any hardware, firmware and software that you re-use or adapt. Diffrerent licences may not be mixed together unless under one umbrella license.

Creative Commons
The most widely used version of Creative Commons is Attribution ShareAlike. This requires anyone making a derived work to give proper attribution to the original author(s) and to use the same licence for any derived works.

GNU GPL
Any material that can be copyrighted can be licensed under the GPL. The GNU people encourage people to charge as much as they wish or can, as an opportunity to raise funds for development.

OSHW
The Open Source Hardware (OSHW) license is specifically designed for open hardware.

Others

 * CERN Open Hardware Licence
 * The TAPR Open Hardware License
 * MIT
 * BSD