Libel involves written or published statements, unlike slander, which is spoken. Posting false accusations on social media can be considered libel.
Pro Tip 2/3
Public Harm
For a statement to be libel, it must be shared publicly and harm someone's reputation. A blog post that falsely claims a teacher stole school funds is libel.
Pro Tip 3/3
Truthful Defense
If a statement is true, it cannot be libel, even if it harms someone's reputation. A journalist cannot be sued for libel when accurately reporting a politician's scandal.