What is SEO? Why does Search Engine Optimization (SEO) matter? With over 240 million people in the United States using the internet and 80% of those people looking strictly at the organic listings in search engines, where your website ranks is extremely important. Google is constantly refining its ranking algorithm; however, there are many things that have held constant over time. This SEO guide will answer the question: What is SEO and how should I be using it?