SEO (Search Engine Optimization) is the practice of optimizing a website or webpage to increase the quantity and quality of its traffic from a search engine’s organic results. The benefits are obvious: free, passive traffic to your website, month after month. But how do you optimize your content for SEO, and what “ ranking factors ” actually matter? To answer that, we first need to understand how search engines work. New to SEO? Check out our SEO basics guide How search engines work Search engines are like libraries for the digital age. Instead of storing copies of books, they store copies of web pages. When you type a query into a search engine, it looks through all the pages in its index and tries to return the most relevant results. To do this, it uses a computer program called an algorithm. Nobody knows exactly how these algorithms work, but we do have clues, at least from Google. Here’s what they say on their “ How search works ” page: To give you the most useful information, S