Most people have at least heard of the term “open source” but the wide popularity of open source has been in software rather than hardware. Open source software is well known. Home computer users recognize it in downloads like Office Libre, GIMP, and the VLC media player. More serious computer users realize that much of the Internet itself was built on open source technologies like Linux and the Apache Web Server. Open source software can quickly be defined as source code that anyone can inspect, modify, and enhance.

Although open source hardware has also been around for a long time, it is considerably more complicated. This is because open source software has code which is something tangible that can be shared. Reproducing and modifying it has no cost other than the developer’s time. Open source hardware costs money to produce. The developer gives away all manufacturing and design files and other pieces necessary to allow recreation and derivatives of the work. Open source hardware developers also give people the complete freedom to sell or do whatever they want with the hardware. Anyone can duplicate the product, but they have to not only invest time in the creation but also have to invest money in the hardware development process.
OSHW (Open Source Hardware) has posted their current 12-point open source hardware definition and statement of principles at the FreedomDefined website. If you are at all interested in open source hardware, this will provide an interesting read. Aficionados of open source hardware are very strict in wanting everyone to adhere strongly to the sharing spirit of the idea of open source hardware. This demands that all types of documentation, necessary software, and design files be included with the open source hardware.
Licensing is also an issue. Varieties of licensing from Cern to Creative Commons are available. In the spirit of the open source hardware movement, you must share your product. If you make changes to the product you are obliged under the spirit of the open source hardware community to share your creation under the same license that it was created with.
Why would anyone want to create open source hardware when he or she is actually giving their work away for free? There are many reasons. Some are altruistic, but there are also many people who have become quite well-known and well-paid for their work because they created open source products. In the spirit of the open source community, attribution for the work is freely given. In fact, most licenses have attribution clauses so that the work of the developer is known. Such a developer can easily be found and known and be offered lucrative work.
Again in the spirit of the community, many knowledgeable people would rather pay money to the original designer than to someone who tries to undercut them using their own design.
Arduino is a classic example of a successful open source hardware project. This is an open source company that manufactures microcontroller-based kits and parts for building digital devices.  Microduino makes versions of these, often in smaller form factors. Both have become well-known viable companies in the open source marketplace.
Both Arduino and Microduino specialize in chips and other electronic components, which is a huge part of the open source hardware market. These companies and others of this type often sponsor contests with the provision that participants share their designs. The Circuit Cellar magazine often promotes these contests. Similarly there are Maker Faires just about everywhere in the world which feature sharing and creativity. You will find a large and welcoming on-line open source hardware community. This year there will also be an Open Hardware Summit in Portland, Oregon on October 7^th. In the spirit of the open source hardware community, getting together and sharing is a very good thing.