A quick note on Academia.edu and ResearchGate
Two options that are often presented to scholarly authors to distribute your works openly are Academia.edu and ResearchGate. It's important to remember that unlike open access repositories, both of these are commercial enterprises (despite the former's top-level domain). That means they're in the business of selling things, including your user data. Please be cautious with utilizing such systems, and consider using open access repositories instead!
For a quick but thorough run-down of the issue, check out this post from Erzsébet Tóth-Czifra, and this broader guide to choosing and using academic sharing and networking platforms for Cornell's Gail Steinhart.
Glossary of Terms
Addendum - A legal document that describes additional terms to a prior agreement. It must be signed by both parties and incorporated as a part of the prior agreement.
Author rights/literary rights - Synonyms for copyright. Neither term has any legal significance.
Copyright - A legal protection for creative intellectual property works.
Copyright license - An agreement to permit another party to use all or some of their copyrights. Typically for a limited duration. E.g., Copyright owners should license to publishers the rights to copy and distribute their work so it can be disseminated in a professional publication, while they simultaneously retain their copyrights so they may also use their work.
Copyright transfer - A complete relinquishment of rights from one party to another. E.g., Many publishers prefer a complete copyright transfer so the publisher can use the work as they desire.
Embargo - A period of time in which an author or publisher prohibits the other party from making the underlying work publicly available.
Exclusive license - An agreement permitting only one other party to use all or some of a copyright owner's rights. Typically for a limited duration. E.g., Publishers often prefer an exclusive license, which gives them the right to be the only party to engage in certain activities such as reproduction and distribution.
Irrevocable license - An agreement that cannot be changed or terminated. E.g., Most publishers prefer an irrevocable license because it ensures they can continue to engage in the rights granted to them in perpetuity.
Non-exclusive license - An agreement permitting one or more parties to use all or some of a copyright owner's rights.Typically for a limited duration. E.g., A copyright owner may enter into multiple non-exclusive licenses with multiple parties such that Party A has a license to copy and distribute for one year, but Party B has a license to copy, distribute, and publicly perform for three years.
Preprint - The author's final draft of a publication, before it undergoes peer review.
Postprint - The author's final draft of an accepted publication, including all changes made as a result of the peer review process, but before publisher copy editing and formating.
Revocable - An agreement that can be changed or terminated. E.g., Most authors should seek revocable licenses with publishers because it ensures the authors can end an agreement and retain the rights they licensed to a publisher.