What Are Internal and External Links?

The customer has an answer. What do they need next?

In Lesson 13, we organized the headings on the water heater repair page for ClearFlow Plumbing, our fictional business in Austin, Texas. That made it easier for someone to find the information they needed without reading every line.

Now imagine another homeowner in Austin, Texas, who hears an unfamiliar noise coming from their water heater. They aren't ready to book a repair yet. First, they want to know what information would be useful to share with a plumber.

They find a helpful article on ClearFlow's website called “What to Tell a Plumber About a Water Heater Problem.” The article explains what details a homeowner could describe when asking for help. By the end, the reader understands what information to share. But they're left wondering: Does ClearFlow offer the repair service I might need?

ClearFlow already has a separate page explaining its water heater repair service in Austin. The article could guide the reader there with one simple sentence:

If you'd like to ask ClearFlow about repairs, read about our water heater repair service in Austin.

The words water heater repair service in Austin can be made clickable. When the reader selects them, the service page opens. That is a link. You can try it in the example below.

A link is a way to move from one webpage to another. It can appear as words, a button or even an image. In this lesson, we'll focus on links made from words, because they are easy to add naturally while explaining something.

An internal link stays on the same website

Look closely at the two addresses in our example. The article is on clearflow.example, and the repair page is also on clearflow.example. The page changes, but the website stays the same.

That is called an internal link: a link from one page to another page on the same website.

Internal links help customers move through a website in a useful order. A person reading an article can reach a related service page. Someone viewing a service page can follow a link to a helpful explanation. A visitor ready to make contact can find the Contact page.

Internal links can also help Google discover other pages on a website and understand how those pages relate to each other. Remember crawling from Lesson 3? Links are one of the ways Google can find pages it may not have discovered yet. That doesn't mean every linked page will be indexed or rank well, but a sensible path makes the website easier to explore.

Why does knowing this help with SEO? Because it helps you see when a page leaves the visitor with nowhere useful to go next. You can improve the journey without writing a new page or trying to force a keyword into the content.

The words you link matter too

Now imagine the article ends with: “For more information, click here.” The words click here don't tell the reader what they are about to open. They're even less useful to someone scanning only the links on the page.

Compare that with: “Read about our water heater repair service in Austin.” Before selecting it, the reader has a much clearer idea of the destination.

The visible words someone can select are called anchor text, or simply link text. Good link text sounds natural in the sentence and tells people what they'll find next.

You don't need to repeat a long list of keywords in every link. That can make writing awkward. A short, accurate phrase is better than a vague instruction or a pile of search terms.

An external link goes to another website

What if ClearFlow's article mentions that some homeowners also want to understand how water heating uses energy? ClearFlow doesn't need to explain every part of that subject itself.

It could point readers to a relevant resource from the U.S. Department of Energy, which publishes information about water heating. ClearFlow would still own its article, but the extra resource would be on a different website: energy.gov.

That is called an external link: a link that takes someone from your website to a different website.

Here's the difference in our example. Linking from ClearFlow's article to ClearFlow's repair page is internal. Linking from ClearFlow's article to the Department of Energy's water heating information is external.

An external link is useful when another reliable source can help the reader check information or learn more about something you mention. But we still have to choose carefully: the source should be relevant, credible and appropriate for the statement we're making. Just because a page is linked doesn't mean everything on it is correct.

And linking to a well-known website isn't a trick that automatically makes your page rank higher. The purpose is to help the person reading.

Do we need lots of links for better SEO?

Not necessarily. Return to the homeowner reading ClearFlow's article. One link to the repair service makes sense because it gives them a helpful next step. A link to an official information source could make sense if the article discusses that source's topic.

But adding ten unrelated links would probably make the article harder to read. The customer didn't come to the page to follow a maze of links. They came for an answer.

It's also worth checking that links still work. If a business moves or deletes a page and forgets to update its links, someone may reach an error instead of the information they expected.

In Lesson 4, we learned that AI answers sometimes include sources or citations. Clear links and reliable sources can help people and search systems explore information, but adding a link doesn't guarantee that an AI assistant will cite or recommend a business.

Why this matters when you're doing SEO

Think about the improvements we've made to ClearFlow's website so far. We chose useful pages, made the service page clearer, organized its headings and now connected the article to a relevant next step. These aren't separate tricks. They're parts of one experience.

When you review a page, ask yourself what the visitor needs after reading it. Is there another page on your own website that would genuinely help? Is there an outside resource worth checking? Can the linked words tell someone where they're going?

That's how links fit into SEO: they connect information for readers and help search engines understand and discover relationships between pages. The decision isn't “How many links can I add?” It's “Which link, if any, would make this page more useful?”