Search Engine Optimization (SEO) refers to techniques that help your website rank higher in organic search results, making your website more visible to people looking for your product or service via search engines.
SEO is a part of the broader topic of Search Engine Marketing (SEM), a term used to describe all marketing strategies for search. SEM is both organic and paid search with paid search, you can pay to list your website on a search engine so that your website shows up when someone types in a specific keyword or phrase. Organic and paid listings both appear on the search engine, but they are displayed in different locations on the page.