Copyright and Subscription-based Publishing
It is often the case that in publishing your research results in a subscription-based journal you will need to sign a copyright transfer or copyright assignment form. This means that you no longer own the copyright in that work, and may be prevented from doing things like revising and adapting the paper for new publication, re-using the paper as a chapter in a book, distributing copies to colleagues, and so on. Note you may still be able to do this if the publisher agrees, but the decision rests with the publisher, not you. Publishers can then, for example, charge high fees to members of the public to read your paper.
Sometimes the agreement you sign with a publisher might be less restrictive, and if you are unsure, or wish to amend the standard copyright agreements requested by a publisher, then you should discuss with your publisher alternatives.
Copyright and Open Access Publishing
Open Access to academic outputs is not just about free access to academic outputs - it is also concerned with being more explicit and more open about the potential uses of those outputs. Open Access publishing does not require academic authors to give up their copyright in the same way as subscription-based publishing. Outputs available on an Open Access basis can, depending on the licensing terms used for their publication, be downloaded for offline reading, printed and distributed to students, be open to automated text mining, and so on.
Note that publishing your work on an Open Access basis does not involve giving up all rights in your work - indeed, as the licensing terms are looser than the "all rights reserved" model, publishing your work on an Open Access basis gives you more control of how your work is distributed, allowing you to post your work in an online repository, re-use it in other publications, and so on, while freeing other users of your work from worries that downloading your work might be illegal.
Creative Commons Licences
One of the most common ways of licensing publications on an Open Access basis is to use a Creative Commons licenses.
Creative Commons licences are ways of informing readers what they can and can't do with a published work, and offer a middle ground between the "all rights reserved" approach of copyright and the "anyone can do anything" approach of the public domain - in other words, the philosophy of Creative Commons can be summarised as "some rights reserved".
Creative Commons licences provide a range of limitations that can be placed on the use of a published work - you can discover the variety of limitations at the Creative Commons choose a licence web page. For example, you could allow people to freely distribute your work but not alter it in any way; allow people to alter your work, but derive no commercial advantage from it; and so on.
When applying for the payment of Gold Open Access fees, papers must carry a Creative Commons Attribution licence, abbreviated as CC-BY. This is a very open licence that allows academic publications to be distributed freely, text mined, and incorporated into other works, provided that attribution is given to the authors.