There’s a whole host of different factors that influence your relevance and authority, and some of them are more influential than others.
For instance, the words someone types into a search engine are important because that search engine wants to give them the best match possible. If you use those words in the body of your web content, the search engine will consider your site more relevant to that search query and rank it higher. We call these keywords, and discovering the best keywords for you to use is critical for relevance as well as overall SEO success.
Search engines look at more than just your words; they also check to see if other websites link to yours. If a high-quality site posts a link to your site, a search engine thinks “Hey, this site I trust has a link to this other site, so the other site must be trustworthy too.” These backlinks are another important factor for SEO, but building enough of those links to help your search rankings can take a lot of time and effort.
Naturally, where there’s value to be had, there’s people looking to game the system. “Black hat” optimizers seek to use any unscrupulous tactics they can to get search ranking advantages. Practices like repeatedly overusing keywords (“keyword stuffing”) or paying somebody to host a link to your website (“paid linking”) were common for many years. However, search engines are constantly updating their algorithms to fight such practices, and will penalize any site caught using them.