What Is SEO? An Intro to Search Engine Optimization

Rachel Handley

Nov 25, 202411 min read
Contributors: Christine Skopec, Connor Lahey, and Selina Scheumann
What Is SEO
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TABLE OF CONTENTS

What Is SEO?

SEO stands for search engine optimization. It is the process of making your website more visible in search engines like Google without paying for ads.

SEO is sometimes called SEO marketing, SEO optimization, or organic search marketing. It can help you earn organic (unpaid) rankings like this:

Google's top organic result for "best hiking boots" is REI with a page called "The Best Hiking Boots of 2024: Tested"

As a result, you can gain more brand awareness and traffic.

SEO involves making your site more appealing to both users and search engines.

The four main elements in a well-rounded SEO strategy are:

  • Keyword Research: Finding out what your target audience searches for
  • On-Page SEO: Optimizing webpages and their content
  • Off-Page SEO: Getting other sites to link to your site, which can boost its reputation
  • Technical SEO: Improving your site's overall performance and accessibility

You will learn more about these elements later.

Search Engine Marketing vs. Search Engine Optimization

Search engine marketing (SEM) promotes a business through unpaid or paid results on search engines, often both.

  • SEO is the subset of SEM that focuses on organic results. It generates traffic that you don’t have to pay the search engine for.
  • Pay-per-click (PPC) marketing is the subset of SEM that focuses on sponsored (paid) results. It involves setting up ad campaigns, paying to run them, and generating traffic.
SEM is a combination of SEO, organic search results, and PPC, paid search results

Paid results don’t always appear on search engine results pages (SERPs). When they do, they usually appear at the top with a "Sponsored" or "Ad" label.

Like this:

The paid result has a bolded "Sponsored" label while the organic result does not

PPC can give you immediate visibility for high-value keywords, whereas SEO can take weeks or months to show results.

However, organic results tend to have higher click-through rates because users often trust them more than ads. Organic results can also generate sustained traffic at little to no ongoing cost.

Why Is SEO Important?

SEO is important in digital marketing because it helps you capitalize on the organic brand awareness and traffic that search engines generate.

For example, this brand’s SEO strategy yields around 7.4 million monthly visitors, according to Semrush’s Organic Research tool:

rei.com has 7.4M traffic for September 2024

If you don’t use SEO, you’re unlikely to rank prominently for relevant terms. This limits your ability to reach new prospects and persuade them to convert.

Users will probably go to a competitor instead.

A higher ranking typically translates into more impressions and a better click-through rate.

The higher the ranking on mobile and desktop, the more likely a searcher clicks through

Since website SEO improves the user experience, it can also lead to better engagement and conversion rates, plus increased traffic from other sources—not just search engines.

Ultimately, SEO can deliver a good return on investment.

How Does SEO Work?

SEO works by aligning your website with how search engines define good search results.

Search engines use complex processes and criteria to rank results, aiming to provide users with the best search experience.

By optimizing your website and content according to these systems, you can gain more visibility.

However, SEO is not a perfect science.

Search engines are somewhat secretive about the systems they use and constantly change them to improve search results.

Therefore, testing, analysis, and adaptation are crucial to SEO success.

How Do Search Engines Work?

Search engines work by crawling, indexing, and ranking content on the internet.

Here’s what each process involves:

  • Crawling: Search engines use automated programs called bots or crawlers to explore the web and discover content. They primarily follow hyperlinks to find new pages.
  • Indexing: After analyzing the content, the search engine determines if it’s eligible for indexing. If it is, the content is added to the database of possible search results.
  • Ranking: When a user enters a query, the search engine tries to understand the search intent. It then uses a complex algorithm to present the best results from its index.
How search engines work: you publish content on your site. Google bots or "spiders" crawl your site and review pages. Google indexes your page. Then, if your page meets the ranking criteria, Google will show it in its search results

When your content appears in search results, it can take various forms, such as traditional search listings (the standard blue links).

Google also displays SERP features (non-standard results) to enhance the search experience.

For example, this SERP includes a popular products section:

Popular products appear below paid results in the SERP

The SERP also includes rich snippets, which are normal results with extra elements like images and star ratings:

REI's tents page has local location info, an image, star rating, and info on delivery and returns on the SERP

Factors that influence your presence, positioning, and appearance on the SERP are known as ranking factors. They include:

  • The relevancy and quality of your content
  • The presence of keywords on your page
  • The number and quality of links from other sites, which can boost your reputation
  • How you use schema markup to help search engines understand and categorize information on your site
  • The speed and usability of your site

Types of SEO

Here are some of the most important types of search engine optimization marketing:

On-Page SEO

On-page SEO is the process of optimizing webpages to improve their search visibility. It focuses largely on using keywords effectively.

Keywords are relevant search terms you want the page to rank for. They help show search engines and users that your content is relevant to their search.

Incorporating your keywords into the body content and the following locations when it is natural to do so is best practice:

  • Title tag: The HTML page title that can appear in SERPs
  • Meta description: The HTML page summary that can appear in SERPs
  • H1 tag: The HTML element that contains the on-page title
  • Subheading tags: HTML tags that contain subheadings (H2s, H3s, etc.)
  • Alt text: HTML image descriptions
  • URL slug: The unique part of the webpage address

Avoiding keyword stuffing—forcing in keywords where they do not belong—is also important because Google considers this a spammy practice. Violating Google's spam policies can lead to a penalty that harms your search visibility.

Off-Page SEO

Off-page SEO refers to actions you can take outside of your website to improve its search visibility.

It most commonly involves link building, which is the process of getting other high-quality websites to link to your website.

These links are called backlinks, and they can help your SEO by signaling that your website is useful and trustworthy.

external websites provide backlinks that allow users to click through to your site

Other off-page tactics like social media management, online reputation management, and email marketing can indirectly benefit your SEO by driving brand awareness and engagement.

Technical SEO

Technical SEO involves improving the technical aspects of your website to enhance its search visibility.

Ensuring that search engines can crawl and index your website properly is the most important aspect of technical SEO. This may involve:

After ensuring proper crawling and indexing, focus on user experience factors such as page speed, website security, and mobile-friendliness.

Image SEO

Image SEO is the process of optimizing images on your website to make them appear more prominently in search results and enhance your overall SEO performance.

For example, image optimization can help you gain exposure like this:

A carousel shows tent size images from various sites at the top of the SERP.

Common image SEO tactics include:

  • Resizing and compressing images to improve page load speed
  • Adding alt text (HTML image descriptions) to help search engines and users with screen readers understand what images depict
  • Ensuring images are visually appealing and useful to your audience

According to Semrush Sensor data from September 2024, Google displays images in the top 20 results for over half of U.S. SERPs. Many users also go directly to Google Images.

Therefore, image SEO provides a significant opportunity to drive traffic to your website.

Video SEO

Video SEO is the process of creating and optimizing videos for maximum visibility in search results. This includes results on search engines like Google and video platforms like YouTube.

Videos listed on the SERP

Common video SEO tactics include:

  • Performing YouTube keyword research to discover what videos users search for
  • Adding keywords to your video title and description
  • Using schema markup to help search engines understand embedded videos

Local SEO

Local SEO is the process of improving your visibility in location-based search results.

For example, when someone searches "outdoor store near me" or "[CITY] outdoor store":

A local search shows relevant places and a map of the area on Google Maps

Local SEO is important if you serve customers in a specific area or have brick-and-mortar locations people can visit.

One of the most important factors in local SEO is optimizing your Google Business Profile because Google evaluates and ranks profiles (rather than webpages) in map-based results.

A "place" is expanded to show its Google Business Profile.

Other tactics include:

  • Listing your business in online directories
  • Encouraging and responding to Google reviews
  • Publishing localized content on your website

How to Get Started with SEO

To understand SEO and how it works, you need to put it into practice. Here's how to get started:

Conduct a Technical SEO Audit

If search engines can't crawl or index your site properly, your other efforts might go to waste. So it's smart to begin with a technical SEO audit.

Enter your domain into Semrush's Site Audit tool and click "Start Audit."

domain entered into Site Audit

Create or sign in to your free account (which lets you audit up to 100 pages per month). Then, follow the steps to set everything up.

The tool will check your site for over 140 issues.

Once your audit is ready, click the number in the "Errors" section:

This domain shows 30 errors

These are the most severe SEO issues on your site.

Click "Why and how to fix it" for more information about each one. Use the "Send to..." buttons to create tasks for your team in your project management tool or CRM.

"Why and how to fix it" pop up shows more about the issue and how to learn how to fix it.

After you've fixed the issues, rerun the audit to check that everything is working properly.

You should also see your Site Health score improve.

Perform Keyword Research

Keyword research is the process of discovering what search terms your target audience uses.

It is important because it tells you what these users want. Using keywords effectively can also help you rank higher for them.

One way to find keywords is with Semrush's Keyword Magic Tool. Enter a broad starting term related to your business, choose your country, and click "Search."

search for "tent" in Keyword Magic Tool

The tool will gather "Broad Match" keywords that contain your starting keyword or a close variation.

We recommend that SEO beginners filter for keywords with a low keyword difficulty score (KD%).

Like this:

0-29 entered as a custom range in the KD filter

Why focus on low KD% keywords?

The lower the KD%, the weaker the competition from other sites. This makes it easier to achieve a high organic ranking.

This is especially important when you are just starting out in SEO.

keyword results include tents, inflatable tent, beach tent, grow tent, rooftop tent, and more

You can also use these keyword metrics to identify the best keyword opportunities:

  • Intent: The type of search intent behind the keyword. It can be informational, navigational, commercial, or transactional. It indicates what kind of content the typical user is looking for.
  • Volume: The keyword search volume, which is the average number of Google searches each month, according to our data.
  • Trend: How actual search volumes have fluctuated over the past 12 months. This can help you understand if a keyword is seasonal or declining or increasing in popularity.
  • SF: The number of types of SERP features present. Click the number to see which ones they are and get insight into search intent, or click the icon to see the SERP for yourself.

intent, volume, trend, and serp features columns highlighted

When you find keywords you want to target, save them with the "+" button.

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Create Quality Content

To rank prominently for your target keywords, you need to create quality content—accurate and original content that satisfies search intent.

For example, people who search "best [PRODUCT TYPE]" are typically looking for product recommendations, reviews, and comparisons to help them decide which specific product to purchase.

High-ranking brands address that intent by conducting in-depth tests and sharing their findings in a well-written and well-presented blog post:

REI's headlamp product review for "best all-around headlamp"

These pages are also optimized for search.

  • The keyword usually appears in the title tag, H1 tag, body content, and URL slug
  • Internal links should point to other relevant pages on the site
  • Schema markup can help search engines understand the article

When another site links to your URL, it indicates that your page or site is useful and trustworthy.

That's why Google considers backlinks when ranking search results.

You can start building your reputation with Semrush's Link Building Tool.

The tool identifies link-building prospects—sites that might link to you—based on your target keywords and competitors. It gives each opportunity a rating based on:

  • The potential benefits of earning the link: Links from relevant, high-quality domains tend to carry more weight.
  • The expected difficulty in acquiring the link: Some sites provide backlinks more readily than others.
Link building prospects report shows 1700 prospects

The tool then helps you send outreach emails to your prospects and monitor the backlinks you acquire.

Some prospects were moved to the In Progress tab for next steps

Track Your Performance

Track your SEO performance to see if your efforts are working. Then, make adjustments based on what you learn.

First, import your target keywords into Semrush's Position Tracking tool.

The tool lets you monitor your overall organic visibility, where 100% means a top ranking for all keywords and 0% means you rank outside the top 100 for all keywords.

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It also provides a full rankings breakdown for each keyword.

The Rankings Overview table shows the keyword, metrics, and its position over a period of time.

You can sign up for alerts about important ranking changes.

Set up Google Analytics 4 (or an alternative analytics tool) to track SEO metrics like organic traffic and conversions.

GA4 traffic acquisition by session source graph

Remember that it can take weeks or months to see the results of your efforts. Allow enough time before changing your strategy.

Keep Learning SEO

Practicing SEO is the best way to continue your learning journey and could be key to growing your website's revenue.

Before you dive in, make sure to create and explore your free Semrush account.

It provides access to market-leading SEO tools and a wealth of helpful resources, including SEO courses.

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