SEO means “Search Engine Optimization” and is the method that search engine’s like, Google & Bing, use to have your website returned for a certain search query. Which results in free traffic to your website which can help reduce your paid advertising and that all equals a win-win for your business
It would be really nice if websites operated on a “Build it and they will come” theory, unfortunately, that’s not how it works anymore. We are a decade out of that realm.
SEO involves a little of what you actually see on a webpage and a whole lot of what you don’t see, and then a whole lot more.