SEO stands for search engine optimization, which is a set of practices designed to improve the appearance and positioning of web pages in organic search results. Because organic search is the most prominent way for people to discover and access online content, a good SEO strategy is essential for improving the quality and quantity of traffic to your website.

Why is SEO important?

To understand the value of SEO, let's break our definition into three parts:

• Organic search results: the unpaid listings on a search engine results page (SERP) that the search engine has determined are most relevant to the user’s query. Ads (in this context, PPC or pay-per-click ads) make up a significant portion of many SERPs. Organic search results are distinct from these ads in that they are positioned based on the search engine’s organic ranking algorithms rather than advertiser bids. You can’t pay for your page to rank higher in organic search results.

• Quality of organic traffic: how relevant the user and their search query are to the content that exists on your website. You can attract all the visitors in the world, but if they're coming to your site because Google tells them you're a resource for Apple computers when really you're a farmer selling apples, those visitors are likely to leave your site without completing any conversions. High-quality traffic includes only visitors who are genuinely interested in the products, information, or other resources your site offers. High-quality SEO capitalizes on the search engine’s effort to match a user’s search intent to the web pages listed in the SERP.
• Quantity of organic traffic: the number of users who reach your site via organic search results. Users are far more likely to click on search results that appear near the top of the SERP, which is why it’s important to use your SEO strategy to rank relevant pages as highly as you can. The more high-quality visitors you attract to your site, the more likely you are to see an increase in valuable conversions.

If you are an agency or in-house SEO looking for resources to educate your clients or company stakeholders about search marketing, we suggest making a copy of, personalizing, and sharing this presentation on the basics and value of SEO.

How does SEO work?

Search engines like Google and Bing use crawlers, sometimes also called bots or spiders, to gather information about all the content they can find on the internet. The crawler starts from a known web page and follows internal links to pages within that site as well as external links to pages on other sites. The content on those pages, plus the context of the links it followed, help the crawler understand what each page is about and how it’s semantically connected to all of the other pages within the search engine’s massive database, called an index.

When a user types or speaks a query into the search box, the search engine uses complex algorithms to pull out what it believes to be the most accurate and useful list of results for that query. These organic results can include web pages full of text, news articles, images, videos, local business listings, and other more niche types of content.

There are a lot of factors that go into the search engines’ algorithms, and those factors are evolving all the time to keep up with changing user behavior and advances in machine learning. Here's how a group of experts ranked their importance:

SEOs use their understanding of these ranking factors to develop and implement search marketing strategies that include a balance of on-page, off-page, and technical best practices. An organization that hopes to earn and maintain high SERP rankings and, as a result, lots of high-quality user traffic, should employ a strategy that prioritizes user experience, employs non-manipulative ranking tactics, and evolves alongside search engines’ and users’ changing behaviors.

It should be noted that while other digital marketing practices like conversion rate optimization (CRO), pay-per-click (PPC) advertising, social media management, email marketing, and community management are often closely related to SEO, these other tactics are generally outside the scope and definition of traditional search marketing. If you’re interested in learning more about any of these areas, the Moz Blog includes categories related to all of these topics and others, too.

Measure and track your SEO progress with Moz Pro

Moz Pro's research tools and SEO analytics help you take your site to the next level. Take a 30-day free trial on us and see what you can achieve:

Start my free trial

How can I learn SEO best practices?

Moz offers the best resources on the web for learning SEO. If you're completely new to the world of search marketing, start at the very beginning and read the updated Beginner's Guide to SEO. If you need advice on a specific topic or want to explore more content for all levels of expertise, check out all of our learning options below.

SEO Learning Center

You are here! Explore free articles like this one on a wide range of topics, from SEO basics to local search to strategies for mobile and international sites. The Learning Center is organized by topic for easy navigation, and each article includes links to other content you may find useful along the way.

Moz Academy

For those serious about investing in their SEO education, Moz Academy offers an extensive catalog of on-demand coursework, led by expert instructors and designed with hands-on learning in mind. In addition to a variety of courses for all skill levels, we offer the opportunity to earn valuable industry credentials with our world-class certifications in SEO Essentials and Technical SEO.

How-To Guides

Written and compiled by the top experts in the industry, our SEO guides on everything from auditing your site for technical success to hiring the best SEO managers are organized by skill level and available for free.

The Moz Blog

Long regarded as one of the most valuable places on the internet for SEO information, the Moz Blog is easy to explore by category and includes contributions from experts across the industry. The blog houses our popular Whiteboard Friday series as well as valuable updates several times per week on all areas of SEO.