What is Theora?
Theora is a video technology for creating, editing, manipulating, and playing video. This type of technology is often referred to as a video format or codec (a portmanteau of coder-decoder). Theora is a free video format, meaning that anyone is free to use, study, improve, and distribute it without needing permission. Some parts of Theora are patented, but the owners of those patents have granted a permanent, irrevocable, royalty-free patent license to everyone.
Because distribution and improvement of Theora is not limited by patents, it can be included in free software. Distributions of GNU/Linux-based operating systems, such as Ubuntu, Debian GNU/Linux, or Fedora, all include Theora "out-of-the-box". And free software web browsers like Firefox and Chrome support Theora. If we consider the six major usage share of web browsers statistics of July 2009, approximately 25% of Internet users across all of these statistics are using Firefox and 2.5% are using Chrome as their browser. This means that every day a huge number of people are using software capable of playing Theora video.
History
Theora is based on an older technology called VP3, originally a proprietary and patented video format developed by a company called On2 Technologies. In September 2001, On2 donated VP3 to the Xiph.Org Foundation under a free software license. On2 also made an irrevocable, royalty-free license grant for any patent claims it might have over the software and any derivatives, allowing anyone to build on the VP3 technology and use it for any purpose. In 2002, On2 entered into an agreement with the Xiph.Org Foundation to make VP3 the basis of a new, free video format called Theora. On2 declared Theora to be the successor to VP3.
The Xiph.Org Foundation is a non-profit organization, that focuses on the production and mainstreaming of free multimedia formats and software. In addition to the development of Theora, they developed the free audio codec Vorbis, as well as a number of very useful tools and components that make free multimedia software easier and more comfortable to use.
The Web
Support for Theora video in browsers creates a special opportunity. Right now, nearly all online video requires Flash, a product owned by one company. But, now that around 25% of users can play Theora videos in their browser without having to install additional software, it is possible to challenge Flash's dominance as a web video distribution tool. Additionally, the new HTML5 standard by the W3C (World Wide Web Consortium) adds another exciting dimension — an integration of the web and video in new and exciting ways that complement Theora.
Patents and Copyright
The world of patents is complicated, leaving plenty of room for Theora's competitors to spread fear, uncertainty, and doubt ("FUD") about its usefulness as a truly free format. In essence, Theora is free. It is free for you to use, change, redistribute, implement, sell or anything else you may like to do with it. But it's important that supporters of free formats understand the questions that arise.
One commonly spread fear is that Theora infringes on submarine patents — patents nobody knows about yet that the makers of Theora never had the authority to use. However it is also true that all modern software could infringe on submarine patents — everything from Microsoft Word to the Linux kernel. However millions of people and entire industries still use these tools. In other words, submarine patents are a problem for the software industry as a whole, however, this doesn't mean that the software industry should stop developing software.
It is also important to note that in a worst-case scenario, even if a submarine patent "emerged", Theora could probably work around it; as this sort of thing happens all the time. Large organizations like the Mozilla Foundation and Wikipedia have examined this issue and have come to this same conclusion.
The software produced by Xiph.org is also subject to copyright, and made available under free software licenses. Xiph.org provides code so that anyone can include it in any application. Xiph.org also provides a set of tools for working with Theora files. This means you can study, modify, redistribute and sell anything you make using Theora or any of the tools provided with it.
Other Free Video Formats
It is worth noting that there is another project creating a royalty-free, advanced video compression format. It is called Dirac. Originally created by the BBC Research department, Dirac will in the future try to cover all applications from Internet streaming to Ultra-high definition TV and expand to integrate with new hardware equipment technologies. Nevertheless, Ogg Theora lends itself extremely well to online (streaming) video distribution, whereas Dirac will likely become a better choice for sharing video files that are of high-definition footage.