Search engine optimization or SEO is fine-tuning a website so that customers looking for businesses like yours can quickly find you on search engines.
Search engines index and rank websites according to content and the number of hits they get. A free technique you can try on your own website is modifying the content and structure of the text to match likely searched keywords.
It’s not just keywords that matter, though. Links are important too. Because search engines also look for words that match your website content, your website ranking may be disadvantaged if the content and links don’t match. To take an obvious example, if you’re selling shoes, it boosts your SEO to have links related to footwear.