At the 2001 meeting that launched the Budapest Open Access Initiative (BOAI) the newly-fledged OA movement outlined two strategies for making the scholarly literature freely available.
Later dubbed green OA and gold OA, these are now the two primary means of providing open access, and both types have been mandated by research funders in the UK.
For instance, in 2013 Research Councils UK (RCUK) introduced an OA policy that favours gold open access, and in 2014 the Higher Education Funding Council for England (HEFCE) announced
what is essentially a green OA policy, which will come into force next year.
So how does the future for open access look?
Some commentary is available here: