Although Nature and the Nature journals are built on a business model funded by subscribers and other sources of revenue, various initiatives have been implemented to enhance the accessibility of the research papers published in these journals.

They have long been freely available to researchers in the 100 or so poorest countries through the World Health Organization's Hinari initiative and others like it. Machine access is being enhanced by the open text-mining initiative of the Nature Publishing Group (NPG) (http://opentextmining.org). Preprints of original versions of papers can be deposited in arXiv (http://arxiv.org) and Nature Precedings (http://precedings.nature.com) without compromising their acceptability for publication. And final authors' versions of papers can be deposited in PubMed Central and other public servers from six months after publication. Authors retain copyright of their work, whereas NPG retains the licence to publish it.

For many years, a more generous arrangement has been made for papers reporting full genome sequences. (The paper reporting the sequence and analysis of 12 species of Drosophila is the most recent example, see Nature 450, 203; 2007). These papers are freely accessible on NPG's website from the moment of publication. This recognizes a consistent character of 'genome' papers: they represent the completion of a key and fundamental research resource, describing and reflecting on what has been revealed but not usually providing insights into mechanism. Although some papers in other disciplines might also be characterized in this way, the fundamental character of the genome has led NPG to make a systematic exception.

In the continuing drive to make papers as accessible as possible, NPG is now introducing a 'creative commons' licence for the reuse of such genome papers. The licence (see http://www.nature.com/authors/editorial_policies/license.html) allows non-commercial publishers, however they might be defined, to reuse the pdf and html versions of the paper. In particular, users are free to copy, distribute, transmit and adapt the contribution, provided this is for non-commercial purposes, subject to the same or similar licence conditions and due attribution.

In 1996, as human genome sequencing was getting under way, leading players stated: “It was agreed that all human genomic sequence information, generated by centres funded for large-scale human sequencing, should be freely available and in the public domain in order to encourage research and development and to maximise its benefit to society” (see http://www.ornl.gov/sci/techresources/Human_Genome/research/bermuda.shtml). These principles have continued to guide the field, and NPG has consistently made genome papers freely available in keeping with them. This new licence allows us to formalize the arrangement.