Cannibalization (or keyword cannibalization) happens when two or more pages on the same website are optimized for, and therefore compete for, the exact same or very similar keywords. This confuses search engines about which page is most authoritative or relevant for a given query, potentially leading to neither page ranking well, or the wrong page ranking.
Instead of consolidating your authority into one strong page, cannibalization splits your SEO efforts, diluting link equity, click-through rates, and overall visibility. It can also lead to a poor user experience if users land on a less relevant or less comprehensive page than what they were expecting.
For developers managing documentation or a knowledge base, this can be a common issue. For example, if you have one article titled "How to Install Docker on Ubuntu" and another titled "Installing Docker on Linux" that largely covers the same steps for Ubuntu, you might be cannibalizing your own content. To fix this, you would consolidate the content into one definitive guide, use a canonical tag to point to the preferred version, or differentiate the content significantly to target distinct long-tail keywords. Regularly auditing your content for keyword overlap is crucial to prevent this SEO pitfall.