Open source software is free, can be modified and shared by everyone.
Open source hardware grants everyone the right to study, to modify, to make and to distribute/sell the hardware.
For more information on open source software licenses, please refer to the pages of the Open Source Initiative: https://opensource.org/licenses.
For licenses we recommend using copyleft licenses (also referred to as "share-alike" or "viral"), which require derivative works to be released under the same license as the original. Common copyleft licenses include:
- CERN Open Hardware License (OHL)
- GNU General Public License (GPL)
- Creative Commons Attribution-ShareAlike (CC-BY-SA) License
- TAPR Open Hardware License (OHL)
Even though patents are expensive both financially and in terms of investment in time, patents and open hardware licenses can potentially be combined. The open hardware license would still ensure a free and non-exclusive use of the patented hardware.
Copyright does not apply to hardware in the way that it does to software. Without a patent, hardware (except for software and design elements) will not be protected by an intellectual property (IP) right. Without an underlying IP, no permission to copy, modify or build upon the hardware is needed and therefore, license terms (like "copyleft" terms) generally cannot be enforced. (Ref: http://www.oshwa.org/faq/#noncommercial)
F.e. CernOHL works with Patents. The CernOHL includes a non-exclusive licence to those patents or registered designs that are held by, under the control of, or sub-licensable by the Licensor, to the extent necessary to make use of the rights granted under the licence. (section 3.5 CernOHL)