Open access relies on the consent of copyright holders to share their work, but making material open access will not deprive copyright holders of any rights.
Copyright holders normally consent to the unrestricted reading, downloading, copying, sharing, storing, printing, searching, linking, and crawling of the full-text of the work. Authors can attach licenses to their work to protect their rights, i.e. block the distribution of mis-attributed copies or commercial re-use, for example, while still permitting legitimate scholarship.
Creative Commons have developed a series of licences that cater for different access and re-use requirements. Publishing under a Creative Commons licence permits users to make use of your work in various ways, but only under certain conditions. The copyright owner can select the type of licence that best suits their needs.
The limited copying and dissemination rights in the Copyright Act make most sense where a copyright owner wants to retain maximum control over, for example, a commercially produced copyright work. Whereas a CC licence can be used enable dissemination and increase the visibility of your work.
What content is covered?
A CC licence covers any content that you are the copyright owner of including original written, photographic and artistic content that you have created and which you control the rights to. If you have previously published the content elsewhere, or entered into any type of assignment or licensing agreement, it is likely you do not control the relevant rights.
How do I assign a Creative Commons licence?