What online activity is protected by the First Amendment, according to a recent federal appeals court ruling?

A recent 4th U.S. Circuit Court of Appeals ruling in Richmond, Va., reversed a lower court ruling, setting a precedent that protects those who express their opinions on Facebook by “Liking” comments, posts or people. The American Civil Liberties Union (ACLU) and Facebook applauded the decision, and an ACLU lawyer commented that the First Amendment protects free speech offline and online.