It is important to remember that posting or uploading anything to the internet counts as publishing. Just as you would not publish someone else’s journal article or photographs in a book without their permission, the same applies to the internet. Even if you are only communicating via social media with one or two individuals, remember that whatever you post is generally public and the world can see it!
Many of these social media sites have no copyright filter, so they will not necessarily prevent you from uploading copyrighted content. If a claim is made against something you have uploaded, the site will most often remove the content and sometimes suspend your account. Under the licence you agreed to when registering for an account, you are liable for anything you upload, not the website.
Remember, just because something is easy to do, that doesn’t make it legal. The internet has made the redistribution of copyrighted material very simple, and it is easy to fall into the trap of ‘everyone else is doing it, so it must be okay’. Think about what you want to share before doing so – if you didn’t create it or you don’t have permission, whether granted specifically to you or granted openly via a copyright statement or open licence, don’t share it! Linking to material on another site or wherever you found it is always better than uploading it yourself.
It is always important to read the terms and conditions of any social media site before registering for an account. In most cases you will retain the copyright to anything that you create or post using the social media site; however, almost all of these sites have a clause that states that you are granting them a world-wide, non-exclusive, royalty-free licence (often with the right to sublicense) to use, copy, adapt, process, distribute, publish etc.
In effect, this means that you continue to own your content, but that FaceBook (or Twitter or LinkedIn or any of the others) have the right to use your material in any way they see fit, without paying you or even asking your permission!
The simple answer to avoiding finding your material appropriated and shared without your permission on social media is don’t put it up there in the first place. You can discuss research, opinions, material etc. without sharing it; and if you do wish to provide material to someone else via the internet, there are private file-sharing or cloud-hosting services you can use.
If you do wish to share something via social media, be sure to put a clear copyright statement on it. This may not protect you from your material being appropriated, but it does mean that those using it cannot plead ignorance, and it will be easier for you to request your material be removed from whichever site is hosting it.