Internal Linking

What Are Internal Links?

An internal link is any hyperlink that points from one page on your domain to another page on the same domain. Internal links are distinct from external links (which point to other websites) and backlinks (which come from other websites pointing to yours).

Internal links serve three critical SEO functions:

• Crawlability: Google discovers new pages by following links from already-known pages. Without internal links, pages become invisible to search engines.
• Link equity distribution: Internal links pass PageRank (ranking authority) from one page to another. Linking from your homepage to a new article shares some of the homepage's authority.
• Contextual relevance: The anchor text and surrounding content of internal links help Google understand what the linked page is about.

A study by Ninja Outreach found that adding internal links to older blog posts increased organic traffic to those posts by an average of 40% within 3 months (Ninja Outreach, 2023).

How Link Equity Distribution Works

Every page on your site has a certain amount of link equity (sometimes called "link juice" or PageRank). When a page links to other pages, it distributes a portion of its equity to each linked page. The more internal links a page receives from high-authority pages on your site, the more authority it accumulates.

Google's original PageRank formula divided a page's equity roughly equally among all outgoing links (Google, 1998). While the modern algorithm is more nuanced, the principle remains: link from your strongest pages to the pages you want to rank highest.

Key principles:

• Your homepage typically has the most link equity (most external backlinks point there)
• Link from your homepage to your most important category and pillar pages
• Use contextual links within content (not just navigation menus) for the strongest signal
• Pages linked from many internal pages accumulate more equity than those linked from few

Anchor Text for Internal Links

Anchor text is the clickable text of a hyperlink. For internal links, you have full control over anchor text, making it a powerful optimization lever. Unlike external link building (where exact-match anchors can look manipulative), using descriptive, keyword-rich anchor text for internal links is standard practice.

Google uses anchor text to understand the topic of the linked page (Google Search Central, 2024). An internal link with the anchor "title tag optimization guide" tells Google that the linked page is about title tag optimization.

Best practices:

• Use descriptive anchors: "learn about title tag optimization" not "click here"
• Vary your anchors: Do not use the exact same anchor text for every link to the same page
• Keep anchors concise: 2-6 words is the sweet spot
• Make them natural: The anchor should fit seamlessly into the surrounding sentence

SEMrush found that pages whose internal links use keyword-relevant anchor text rank 12% higher for those keywords compared to pages linked with generic anchors like "read more" (SEMrush, 2024).

The Hub-and-Spoke Model

The hub-and-spoke model (also called the pillar-cluster model) is the most effective internal linking strategy for topical authority. It works like this:

1. Hub (Pillar Page): A comprehensive page covering a broad topic (e.g., "On-Page SEO Guide")
2. Spokes (Cluster Pages): Detailed pages covering subtopics (e.g., "Title Tags," "Meta Descriptions," "Internal Linking")
3. Bi-directional links: The hub links to every spoke, and every spoke links back to the hub
4. Cross-links: Related spokes link to each other where contextually relevant

HubSpot coined and popularized this model. Their own data showed that implementing pillar-cluster architecture increased organic traffic by 50% and improved rankings for 80% of target keywords within 6 months (HubSpot, 2023).

Orphan Pages: The Silent Traffic Killer

An orphan page is a page on your site that has no internal links pointing to it. These pages are difficult for search engines to discover and crawl, and they receive zero link equity from the rest of your site.

Ahrefs found that 26.2% of pages on the average website are orphan pages (Ahrefs, 2024). These orphan pages receive 87% less organic traffic than properly linked pages covering similar topics.

To fix orphan pages:

• Run a site crawl using Screaming Frog or Ahrefs Site Audit to identify orphan pages
• Add contextual internal links from relevant existing content
• Include the page in navigation menus or category pages if appropriate
• If the page has no value, consider removing it or consolidating it with a related page

Crawl Depth

Crawl depth measures how many clicks it takes to reach a page from the homepage. Google prioritizes pages that are closer to the homepage, crawling them more frequently and assigning them higher importance. A Botify study of 6.2 billion pages found that pages at crawl depth 1-3 get crawled 5x more frequently than pages at depth 5 or beyond (Botify, 2024).

• Depth 1: Directly linked from the homepage (highest priority)
• Depth 2: One click from a homepage-linked page
• Depth 3: Two clicks from a homepage-linked page (the practical maximum for important pages)
• Depth 4+: Decreasing crawl priority and link equity

Running an Internal Linking Audit

Audit your internal links quarterly. Key metrics to check:

• Orphan pages: Pages with zero internal links pointing to them
• Pages with excessive links: Pages linking to 100+ other pages dilute equity per link
• Broken internal links: Links to pages that return 404 errors waste equity and frustrate users
• Crawl depth: Important pages buried deeper than 3 clicks from the homepage
• Anchor text distribution: Overuse of the same anchor text or too many generic anchors

Free tools like Screaming Frog (up to 500 URLs free) and Google Search Console's Links report can identify most internal linking issues. Ahrefs and SEMrush offer more comprehensive internal link auditing for larger sites.