SEO and SEM are two different things. SEO stands for search engine optimization, which is an approach to marketing a business online that is built around optimizing the website to rank better in search engines. SEM stands for search engine marketing, which is a term used to describe paid advertising techniques that utilize the major search engines. The purpose of SEO is to make it easier for people and businesses to find your site. With SEO, you can ensure that you have a high quality site that users will enjoy and want to visit regularly. The purpose of SEM is to drive website traffic through paid advertising, which can be expensive but can also be very effective at generating leads and conversions.