It can be a bit confusing at first, because there are many things that go by the name OpenX. The company OpenX is the developer of the OpenX Ad Server, and it operates two hosted version, OpenX Community Hosted and OpenX Enterprise Hosted. It is offers an online real time advertising market place called OpenX Market.
About the OpenX Ad Server

OpenX Ad Server is the world's leading open source ad server
OpenX Ad Server is a free, open source ad server system. It is available for download, and can then be installed on your own server. There are a number of specialized web hosting companies that offer outsourcing services for the software.
Support for OpenX Ad Server
OpenX Ad Server is a large system, and it will take a bit of effort and energy to get acquainted with it. If you’re switching from another ad server, it will look and feel different for the first few days or weeks. Training for administrators and ad operations staff can help you get started. More advanced techniques (like targeting or tight integration with other website management systems) may also require some external assistance. And if something goes wrong, trouble shooting or recovery services could be very welcome.
For enterprise-level premium services, the team at OpenX Professional Services makes their in-house specialists available. In addition, OpenX maintains a list of consultants, ranging from very experienced, full time specialists to less experienced contractors. I’m also on this list of consultants, but you can also contact me directly for OpenX support by submitting the form on this website.
About OpenX Hosted
In addition to operating a self-hosted OpenX system, publishers and advertisers can also use the hosting services offered by OpenX, called OpenX Hosted. There are two flavors: OpenX Community Hosted is free for anything up to a volume of 100 million ad impressions. For larger volumes, there is the paid version called OpenX Enterprise Hosted, which starts at $999 per month.
About OpenX Market

OpenX Market is a real time market place for online advertising
OpenX Market is an online, real time market place for display advertising. Publishers can use it to auction their unsold inventory, while keeping full control over the minimum price and acceptable ad categories for their site. Advertisers can use the market place to easily reach a large number of specialized publishers, bidding to have their ads displayed on well targeted websites.
Using OpenX Market with the OpenX Ad Server
All of the various flavors of the OpenX Ad Server software mentioned above can be used by publishers to participate in OpenX Market. And advertisers can use OpenX Ad Server too, to manage and measure the ad campaigns they place into the OpenX Market.
About OpenX.org
The company that develops the OpenX Ad Server software, and runs the OpenX Hosted and OpenX Market producs is called OpenX Ltd, officially located in London, UK. Most of the operations are concentrated in a subsidiary called OpenX Technologies, Inc., which is based in Pasadena, California, USA.
