With 20 years of SEO under my belt I have learned many tricks. One item I never leave off my checklist is to plug the site into the W3C Validator. "Oh, please!" some say, "why should I be concerned with W3C validation if I am trying to optimize my site?"

If you want your site to be optimized, it must first be indexed. A site with fatal errors is not going to index properly. And for awhile any webmaster who installed the Meta pixel into the code as instructed would introduce a fatal error. There was a stretch of time where one out of three sites that came to me had a fatal error according to the W3C standard.

Here's where it gets nerdy, so feel free to jump down to the graphic.

W3C stands for Worldwide Web Consortium, which existed to set web standards. Without it, web programmers don't have a common set of standards to use in their web authoring. These standards are flexible enough to cover different types of code. Mostly we don't hear much about these standards because browsers do a good job of handling typical quirks in the HTML and show the viewer what they would see.

There are typically several warnings and probably a few errors. Maybe one time in my entire career have I seen a page with no errors or warnings, and I don't think it was any better of a page because of it. Certainly pages with errors convert every nano second on the web. A fatal error is a more serious error that can create a cascade of further errors, which the validator just shows once. So you have to make sure that you are looking at something serious, or something benign.

But a bot/spider/crawler/whathaveyou is not the same as a browser that can display what the viewer wants to see. It can, when running across a fatal error, just give up. If it gives up, that means the content of a page is inaccessible and any optimization attempted is now neutralized.