When your potential customer is searching, Google uses a complex formula to determine whether or not your website is included in the search results and where it ranks. Basically, Google looks at how your website is setup and how popular your website is (in terms of how many other websites link to yours, how many visitors your website gets, and how much your website and business are talked about on social media sites like Facebook). Search engine optimization (SEO) is the process of improving your website and doing online public relations to make it more popular— in order to show up higher on Google.
The advantage of doing SEO and showing up in the normal search results is that you don’t have to pay anything to Google. The disadvantage is that it sometimes takes a long time to show up on the first page, and it can be an unpredictable process because Google is always changing their formula. With Google Advertising which is called Google Adwords or Pay Per Click, you can show up on the first page immediately.