If your library has a Facebook page and uses it for outreach, you need to read this article from the Dangerous Minds website. There really isn’t a good quote to pull out the meaning, so take a moment to go and read it. The basics revolve around Facebook monetizing page promotion while simultaneously throttling the amount of people who can see a post from a Facebook page.
As someone who loved to mix social media with the assumed dusty and ancient world of archiving and libraries, this article really hits home. It's amazing how, in every way, big companies shut little companies out. If anything, this is a cyber version of what is going on in our country.