Cannibalisation is when two or more of your own pages compete for the same search, so Google keeps swapping which one it shows. Both pages are weaker than one good page would be.
How it happens
Almost always by accident, over time. You write a page about a service. Two years later somebody writes a blog post covering much the same ground. Then a landing page gets built for a campaign. Nobody did anything wrong at any point, and now three pages address one subject.
Google has to choose, the choice is not stable, and the effort that would have made one page authoritative is spread across three that are not.
How to spot it
The signature is a ranking URL that keeps changing for the same keyword while the position bounces around. If you are only recording positions and not which page ranked, this is invisible: you see instability and assume the algorithm is being difficult.
Recording the ranking URL alongside the position is what makes it detectable, and it is why we surface it as an insight rather than leaving you to notice.
Fixing it without deleting work
Decide which page should own the subject, usually the one that already ranks best or best matches what a searcher wants. Then reduce the competition rather than the content: retarget the others at genuinely different questions, merge the good parts into the chosen page, or redirect a page that has nothing unique left.
Internal links matter here. If your own links point at three different pages for one subject, you are telling Google you cannot decide either.
Where this shows up in the tracker
Every term in this glossary is something the product actually measures or acts on. Plans start at £29 a month, with rank tracking, AI visibility, the daily AI readiness scan, security and domain health, Search Console, backlinks and audits on every one of them.
Related terms
Rank tracking
Rank tracking records where your website appears in search results for chosen keywords, checked on a schedule so you can see movement over time. It answers where you are, and it is no longer sufficient on its own to explain what that is worth.
Striking distance
Striking distance keywords are the ones ranking just below where the traffic is, usually positions four to fifteen. They are the cheapest improvements available to most websites, because the hard part is already done.
Canonical
A canonical tag is a line in a page telling search engines which address is the official version, for when the same content is reachable at several different URLs.
Share of voice
Share of voice is your visibility across a whole keyword set, weighted by how much each keyword is searched. It shows how much of the available attention in your market you hold, and who holds the rest.