Knowledge Graph: Topic Mapping and Content Gaps

What Is the Knowledge Graph?

The Knowledge Graph is RnkRocket's topic mapping tool. It analyses your website and builds a picture of the subjects you cover, the relationships between them, and — importantly — the topics you are missing that your competitors are covering or that your customers are searching for.

Think of it as a map of your website's expertise. A well-built Knowledge Graph tells Google that your website is a reliable source on a particular subject, which helps you rank more broadly across related searches.

How It Works

When RnkRocket builds your Knowledge Graph, it:

Crawls your website to understand your existing content and the topics it covers
Analyses search data to identify related topics and questions people are searching for
Compares against competitor content to find gaps — topics they cover that you do not
Groups topics into clusters — collections of related content that support each other

The result is a visual map showing your topic coverage and the areas where new content could strengthen your rankings.

Topic Clusters

Topic clusters are groups of closely related content. A good cluster has:

A pillar page — a comprehensive overview of the main topic
Cluster pages — more specific pages that go into detail on subtopics and link back to the pillar

For example, a plumber's website might have a pillar page on "boiler repair" supported by cluster pages on "boiler breakdown causes", "when to replace vs repair a boiler", and "emergency boiler repair costs".

This structure helps Google understand the depth of your expertise and tends to rank the whole cluster higher than individual pages would rank on their own.

Content Gaps

Content gaps are topics your customers are searching for that you do not currently have pages for. The Knowledge Graph highlights these clearly, ranked by their potential impact on your traffic.

Filling content gaps is often one of the fastest ways to grow organic traffic because you are creating pages for searches that already exist — you are not trying to create demand, just meet it.

Content Ideas

Based on your Knowledge Graph, RnkRocket generates specific content ideas — suggested pages or articles with:

A recommended title and target keyword
The search volume and difficulty for that keyword
An outline of what the content should cover
Notes on how it connects to your existing pages

You can send any content idea directly to Content Studio to generate a first draft.

When Is It Built?

Your Knowledge Graph is built automatically during the onboarding process once RnkRocket has crawled your website. The initial build typically takes a few minutes.

After that, the Knowledge Graph is updated periodically as Autopilot runs its checks and as you add new pages to your site. You can also trigger a manual refresh from the Knowledge Graph page if you have made significant changes to your website.

Getting the Most From Your Knowledge Graph

Review your content gaps monthly and add the top opportunities to your content calendar
Use topic clusters to plan batches of related content rather than creating isolated pages
Prioritise gaps where you already have some existing content — these are quickest to fill because you can expand existing pages rather than starting from scratch
Check how your cluster coverage changes over time as a measure of your content strategy progress
Send high-priority content ideas directly to Content Studio to generate a first draft — this saves time and ensures the draft is aligned with the right keywords
Compare your topic clusters with competitor coverage in the Competitor Analysis section to validate which gaps are worth filling first
If you are unsure where to start, focus on clusters where you already have a pillar page but are missing supporting content — these are the fastest wins

For a broader overview of content planning, see our content strategy guide.