For example: Say you sell real estate in Concord, North Carolina. When a person types "house concord nc" into Google search, you want your website link to be one of the first five pulled up on the search results page. If you're on the first page of the results generated by the search engine, your website has achieved search engine optimization.
Search engine optimization is all about making sure your web site comes up at the top of the list when a person initiates a search. Most web users won't click beyond the first page of search results, so you want your web site to appear at the top of the page.
Since users all think differently, the words and word phrases they use to initiate a search will be different. That's why it's important that your site be rich in a variety of key words and key word phrases to ensure that no matter what words the user types into the search screen, your web site will pop up on the results page.