04 June 2021
At its heart, SEO (Search Engine Optimization) developed as an extension to web accessibility by following HTML4 guidelines, in order to better identify the purpose and content of a document.
This meant ensuring that web pages had unique page titles that properly reflected their content, as well as keyword headings to be better highlight the content of individual pages, and that other tags were treated the same accordingly.
This was necessary, not least because web developers were often only focused on whether their coding worked, rather than the user experience, let alone following web publishing guidelines.
This slowly changed as it became increasingly known that search engines used these "on-page" signals to provide their "Search Engine Results Pages" (SERPs) - and that there was an advantage to ranking higher on these to tap into free and natural organic traffic.
Even in 2021, this is still the case, a state of affairs reinforced by the forthcoming Core Web Vitals, Google's way to signal that it is sort of resetting the clock.