What is Open Access?
As defined by Budapest Open Access Initiative, "by 'open access' to this literature, we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited."
Created by Scholarly Publishing and Academic Resources Coalition (SPARC), here is a three minute video on Open Access 101.
Creative Commons is a set of copyright licenses designed to protect those who wish to publish their works in an open access environment from having those works used inappropriately for commercial purposes. Different varieties of license protect and allow different style of publishing allowing for a great deal of use flexibility. To license information under Creative Commons, or to learn more about their functions, go here.