carbon.txt is a proposed convention to verify that IT infrastucture uses green power.
If a site or digital services supports carbon.txt, you'll be able to trace a path from the site to where the energy it uses comes from, and the steps taken to stop it contributing to climate change.
It does this with governance structures we aleady use - combining the domain name system on the internet, and existing standards and conventions for accounting for carbon emissions from generating electricity used in energy markets today.
See it in use
See it in use on The Green Web Foundation Green Checker
Contribute to carbon.txt
Help shape the carbon.txt spec, to share the information most useful to you
Follow updates on twitter
For new releases, see software using it.