What Is an External Link? Outbound Links Done Right

Aug 11, 2026 · SEO Glossary

In the HTML, it's one attribute's worth of difference. <a href="/pricing/"> points inside your site; <a href="https://other-site.example/study"> points out of it. But that second anchor does something the first one doesn't: it extends your site's endorsement to someone else's page, and search engines read it exactly that way. Everything worth knowing about external links follows from that endorsement mechanic.

What is an external link? It's a hyperlink from a page on your domain to a page on a different domain. From your perspective these are outbound links; the same links, viewed from the receiving site, are their inbound links or backlinks. One anchor tag, two vocabularies depending on which end you're standing on. (Links within your own domain are a separate discipline entirely — that's internal linking.)

What a crawler does with your external link

When Googlebot parses your page and finds an external anchor, several things happen:

• The target URL joins the crawl queue — outbound links are one of the web's primary discovery mechanisms.
• The link is recorded in the link graph as a citation from your page to theirs, weighted by your page's own standing.
• The anchor text is noted as a description of the target — it helps Google understand what the linked page is about.
• The link's context (surrounding text, position in main content vs footer) shapes how much it counts.

Unless, that is, you've qualified the link with a rel attribute — which is where you control the endorsement.

The rel attributes: your endorsement dial

Three values, standardized by Google in 2019, tell crawlers how to treat an outbound link:

• rel="nofollow" — "I'm not vouching for this." The original (2005) qualifier. Since 2020 Google treats it as a hint rather than a directive — it may still crawl and count the link, but usually doesn't.
• rel="sponsored" — "this link was paid for." Required (or nofollow at minimum) for ads, paid placements, and affiliate links. Passing endorsement through paid links violates Google's spam policies in both directions — this attribute is how you stay on the right side of that line.
• rel="ugc" — "a user posted this, not us." For comment sections and forum posts, where you can't vouch for what users submit.

They combine: rel="sponsored nofollow" is valid. A concrete affiliate link looks like:

<a href="https://shop.example/product?aff=123" rel="sponsored">the stand mixer I use</a>

Everything without a qualifying rel is a "followed" link — a full-strength editorial citation. That's the correct default for links you chose to include because the target deserves them.

Does linking out help your own SEO?

The myth on one side: "linking out leaks PageRank, so link out as little as possible." The overclaim on the other: "linking to authorities boosts your rankings." The evidenced middle:

• Google has said there's no ranking bonus simply for linking to authoritative sites.
• But citing real sources is a property of trustworthy content — the kind of content that scores well on E-E-A-T criteria. A page making factual claims with zero sourcing reads as weaker to raters and readers alike.
• Hoarding link equity by refusing to link out is optimizing a fluid-dynamics metaphor from 2008. Link where it serves the reader; the reader is the ranking strategy.

The maintenance problem nobody budgets for

Here's what actually goes wrong with external links: entropy. You don't control the targets, and the web rots underneath you. A content site that's published for five years typically carries hundreds of outbound links, of which a meaningful share now point at 404s, expired domains (sometimes re-registered by spam operators — which means your page now links to a casino), or chains of redirects. Each broken outbound link is a small trust leak for readers and a dead end for crawlers.

The fix is mechanical, which is the good news:

1. Crawl your site and check every outbound URL's response. This is exactly the tedious-but-automatable job a scheduled site audit exists for — it fetches every external target and reports the 404s, timeouts, and redirect chains without you clicking through five years of archives.
2. For dead targets: relink to the page's new home if it moved, swap in an equivalent source, or link to an archived copy when the original is simply gone.
3. For redirecting targets: update the href to the final URL — a target that 301s still works, but pointing at the destination directly is cleaner and survives the day the redirect gets dropped.
4. Re-check on a schedule. Link rot is continuous; a yearly sweep keeps it below the level readers notice.

Judgment calls that come up constantly

Should links open in a new tab? User-experience preference, zero SEO effect. If you use target="_blank", add rel="noopener" — a security measure (it cuts the new page's scripting handle back to yours), not an SEO one.

Linking to competitors? If their page is genuinely the best reference for a point, the link costs you almost nothing and the credibility gain is real. Refusing on principle mostly signals insecurity.

How many external links is too many? There's no number. The test is editorial: does each link serve the reader? A 2,000-word research summary might justifiably carry thirty; a product page might carry none.