SEO stands for search engine optimization. SEO practitioners optimize websites, web pages and content for the purposes of ranking higher in search engines, like Google. SEO is a set of practices designed to improve the appearance, positioning, and usefulness of multiple types of content in the organic search results. This content can include web pages, video media, images, local business listings, and other assets. Because organic search is the top method via which people discover and access online content, utilizing SEO best practices is essential for ensuring that the digital content you publish can be found and chosen by the public, increasing your website’s organic traffic.

How do search engines work?

illustration of web pages connected by spiders and spider webs

In order to understand how SEO works, it’s vital to have a basic understanding of how search engines work. Search engines use crawlers (also known as spiders or bots) to gather information across the internet to populate their big databases, called “indexes”. Crawlers begin from a known web page and then follow links from that page to other pages.

For example, if a page Google already indexed on on the topic of used clothing features internal links to further pages on the site for used jackets, used hiking boots, and used flannel shirts, Google can crawl to those pages via the links provided. Meanwhile, if Patagonia’s main used clothing page links out to an article on about the negative impacts of fast fashion, Google can crawl from Patagonia to the news article via the link, thereby discovering that content and potentially indexing it.

The content of the discovered page, and the context of the links the crawler followed from Patagonia to The Guardian, help Google understand what the page is about and how it is relevant to all of the other pages within its index.

If you happen to be the journalist who wrote The Guardian article on fast fashion, the fact that a used outdoor clothing section of a large brand is linking to your piece is an indication to Google that there might be a relationship between the problems of fast fashion and the potential solution of buying used clothing instead of new clothing. These semantic relationships go far towards helping Google determine which results to show for each query they receive from the searching public.

Search engines’ success as businesses depends on the public finding search engine results to be relevant to their needs. The more links a search engine like Google finds pointing from a particular type of content to a particular resource, the more confident it becomes that the linked-to resource is relevant to certain search queries. The search engine then determines that this resource deserves to be ranked highly when people make those queries.

There are three main categories of SEO: on-page SEO, off-page SEO, and technical SEO, all of which combine to help search engines discover, crawl, index, understand, and rank your content, and this article will cover each of these topics.

Why is SEO important?

A significant reason that SEO matters is because it helps online publishers appear within the results displayed by search engines. Search engines like Google and Bing each have their own methods of surfacing and formatting the content they display when a user enters a query into a search box, like this: