How important is SEO? We often think about SEO in positive terms. Obviously, phenomenal SEO can increase your site’s traffic dramatically over a period of time. But after the release of Google’s Panda, Penguin and Hummingbird updates, it’s also way past time to start thinking about how important SEO is in negative terms. SEO is so important that mistakes—doing it wrong—can literally cost you an 80% drop in web traffic.