What Is SEO? An Intro to Search Engine Optimization

Rachel Handley

Oct 04, 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 (search engine optimization) is an effort to make your website more visible in search engines like Google—without paying for ads. 

It’s sometimes called SEO marketing, SEO optimization, or organic search marketing. And 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"

And get more brand awareness and traffic as a result.

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

There are four main elements in any well-rounded SEO strategy:

  1. Keyword research: Finding out what your target audience searches for
  2. On-page SEO: Optimizing webpages and their content
  3. Off-page SEO: Getting other sites to link to your site—which can boost its reputation
  4. Technical SEO: Improving your site’s overall performance and accessibility

You’ll learn more about these later.

Search Engine Marketing vs. Search Engine Optimization

Search engine marketing (SEM) is the process of promoting a business through unpaid or paid results on search engines—often both.

  • SEO is the subset of SEM that focuses on organic results. It can generate 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 and paying to run them and generate 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). But when they do, they tend to appear at the top. With some kind of “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. 

But organic results tend to have higher click-through rates. Because users often trust them more than they do ads. And organic results can generate sustained traffic at little to no ongoing cost.

Why Is SEO Important?

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

For example, REI’s SEO strategy yields around 7.4M 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. Which limits your ability to reach new prospects and persuade them to convert.

Users will probably go to a competitor instead.

After all, 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

And since website SEO improves the experience for users, 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.

Basically, search engines use complex processes and criteria to rank search results. With the aim of giving users the best search experience.

Working on your website and content with these systems in mind can help you gain more visibility.

That said, SEO is not a perfect science.

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

So, 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 of those means:

  • Crawling: The search engine uses automated programs (known as bots or crawlers) to explore the web and discover content. They primarily do this by following hyperlinks.
  • Indexing: The search engine analyzes the content. If it's eligible, the search engine indexes the content (adds it to the database of possible search results).
  • Ranking: When a user enters a query, the search engine tries to understand search intent (what the searcher wants). 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 is presented in search results, it can take a number of forms. Like traditional search listings (the standard blue links).

But Google commonly displays SERP features (non-standard results) to make the search experience more engaging.

For example, this SERP includes a popular products section:

Popular products appear below paid results in the SERP

There are also rich snippets (normal results with extra elements).

Like this one, which includes an image and a star rating:

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

Things 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 you have from other sites (which can boost your reputation)
  • How you use schema markup (which helps 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’s largely about using keywords effectively.

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

It’s best practice to incorporate your keywords into the body content and the following locations, when it’s natural to do so:

  • 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

It’s important to avoid keyword stuffing (forcing in keywords where they don’t belong). Because Google considers this to be 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 things you can do outside of your website to improve its search visibility.

It most commonly refers to link building. Which is the process of getting other high-quality websites to link to your website. 

These kinds of 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 helping drive brand awareness and engagement.

Technical SEO

Technical SEO is improving technical aspects of your website with the aim of improving its search visibility.

The most important thing is ensuring that search engines can crawl and index your website properly. This may involve:

After that, you can 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 so they may appear more prominently in search results. And help your wider SEO performance.

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

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

Common tactics include:

  • Resizing and compressing images so they load more quickly
  • Adding alt text (HTML image descriptions) that helps search engines and people using screen readers understand what images depict 
  • Making sure images are visually appealing and useful to your audience

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

So, there’s a huge opportunity to earn traffic from your images. 

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 tactics include:

  • Performing YouTube keyword research to see 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 an effort to improve your visibility in location-based search results.

For example, when someone searches “outdoor store near me” or “portland outdoor store”:

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

So, local SEO is important if you serve customers in a specific area. Or have one or more 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 really understand the meaning of 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. And use the “Send to…” buttons to create tasks for your team in Trello, Zapier, or the Semrush CRM.

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

Once you’ve fixed the issues, rerun the audit to check that everything’s 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 audiences use.

It’s important because it tells you what these users want. Plus, using keywords effectively can help you rank higher for them.

One way to find keywords is with Semrush’s Keyword Magic Tool. Enter a broad starting term that’s 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? 

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

This is especially important when you’re 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. This can be informational, navigational, commercial, and/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: How many types of SERP features are 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 headlamps” are typically looking for product recommendations, reviews, and comparisons to help them decide which headlamp to purchase.

REI caters to this 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"

The page appears to be optimized for search, too.

  • The keyword “best headlamps” appears in the title tag, H1 tag, body content, and URL slug
  • Internal links point to other, relevant pages on the site
  • Schema markup helps search engines understand the article

When another site links to your URL, it can indicate that your page/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.

It identifies link building prospects (sites that might link to you) based on your target keywords and competitors. And 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 hand out backlinks more easily than others)
Link building prospects report shows 1700 prospects

The tool then helps you to 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

To see if your efforts are working, track your SEO performance. Then, you can make any adjustments based on what you learn.

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

It lets you monitor your overall organic visibility (where 100% is a top ranking for all keywords and 0% means you rank outside the top 100 for all keywords).

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And gives you 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 even sign up for alerts about important ranking changes.

We also recommend that you set up Google Analytics 4 (or an alternative analytics tool).

This will allow you to track SEO metrics like organic traffic and conversions.

GA4 traffic acquisition by session source graph

Just remember that it can take weeks or months to see the results that come from efforts. So, make sure to 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.

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

It gives you access to market-leading SEO tools. Plus a ton of helpful resources, including SEO courses.

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