Open Access literature is digital, online, free of charge, and free of most (but not all) copyright and licensing restrictions. 
Today there is an increasing expectation that access to research results funded by public authorities, such as the Australian Government, should be free. For many years this was not the case. Worldwide, publicly funded research was often published in distinguished journals, accessible to only a few, and at a further cost (eg, the cost of the journal subscription or access to same). Australia, along with 30+ other countries, signed the Economic Co-operation and Development's Declaration on Access to Research Data From Public Funding. This agreement recognises that open access to, and unrestricted use of, data provides widespread benefit and gain.
Various strategies and services support the principles of Open Access. BioMed Central is an example of an Open Access publisher, providing free access to 185+ peer review journals. An example of one of its journals is BMC Palliative Care, but all are indexed and made freely available on PubMed. The Directory of Open Access Journals provides access to approximately 3,300 free, full text, quality controlled scientific and scholarly journals.