How Does SEO Work?
Search engines aim to find relevant high-quality content to match up with keywords people use to find things on the web. To identify that content among billions of web pages, search engines use automated programs called robots (or spiders) to crawl the websites of the world. To make this process faster and more effective, they reward websites that make it easier to understand the content contained within.
So, at the most basic level, SEO is just the practice of providing information on what your content is about so it can be indexed and understood by search robots.