Technical
Technical SEO means making sure Google can correctly index your site and that you can correctly track traffic to it. It’s incredibly important, as, you can have the best looking website in the world, but Google can’t index it, you won’t be appearing in search results. Similarly, if you aren’t able to track your visitors and their interaction with your website correctly, then you aren’t receiving the correct information to make website decisions.
Most of what’s covered in this section are some common occurrences and how to deal with them, but really, there are nearly endless scenarios to possibly deal with. If you are worried that there is something technically wrong with your website, places like the Google Webmaster Forum is a great place to ask, and of course this is generally where an SEO agency or freelancer who knows what they’re doing can be useful.