An important aspect of SEO is making your website easy for both users and search engine robots to understand. Although search engines have become increasingly sophisticated, they still can't see and understand a web page the same way a human can. SEO helps the engines figure out what each page is about, and how it may be useful for users.
A Common Argument Against SEO
We frequently hear statements like this:
"No smart engineer would ever build a search engine that requires websites to follow certain rules or principles in order to be ranked or indexed. Anyone with half a brain would want a system that can crawl through any architecture, parse any amount of complex or imperfect code, and still find a way to return the most relevant results, not the ones that have been 'optimized' by unlicensed search marketing experts."