Benefits of Publishing Open Access
There are many benefits of publishing your work OA. The clearest one (and the one that is discussed most often) is that more people will be able to read your research. Removing the paywall from a book or journal article removes the biggest barriers to other people reading your work. This allows you to have a much greater influence and impact in your field, reaching anyone with an interest in the topic, rather than just those whose institutions purchase the book or subscribe to the journal.
Another benefit of publishing OA is that it makes it much easier to reuse and adapt your work. OA articles, chapters and books are published under creative commons licenses. While some of these include restrictions (for example, CC BY NC would not allow anyone to reuse your work to make a profit), they all allow a certain level of reuse of your work as long as you are credited as the original creator of it. This means that you could do things like translate your article and publish it in another journal in a different language (always be sure to inform that journal of the circumstances before publication though) or offer a portion of your book to a colleague to use in a text book. There are any number of other ways that you (or anyone else) could reuse and adapt your work for the benefit of the discipline.
As well as increasing the influence of your work and allowing you to reuse and adapt it more easily, publishing OA is sometimes a requirement to obtain funding. Some funders are committed to the idea of OA publishing and will only release funds to you on the condition that you publish your findings in a way that allows anyone to be able to read and reuse them. This means that publishing your book or journal article OA opens up more funding options to you.
