It Usually Falls Into a Recognizable Pattern
Online defamation rarely shows up in a form that's entirely unfamiliar. Most situations fall into a handful of recurring patterns — fake reviews, social media pile-ons, impersonation, personal disputes gone public, and attacks on professional or business reputation. Recognizing which pattern you're dealing with helps you anticipate how it's likely to spread and what response tends to work.
It also helps to know what these situations have in common: they almost always move faster than people expect, they're almost always easier to address early than late, and the poster almost always has some connection to you, even when the account looks anonymous at first glance.