Search Engine Optimization (SEO) is the practice of creating or modifying a website to be friendly for search engines (i.e. Google, Yahoo, etc.), causing them to deliver plenty of organic (i.e. free) and targeted traffic. There are other ways to increase your traffic, such as Pay-Per-Click Advertising (PPC) and Social Media Marketing (SMM). To get the most out of your website, make sure it is search engine optimized.