What entity salience measures
Salience is a score for prominence: given everything a document says, how central is one particular entity to it? A page about the Annapurna Circuit will mention Pokhara, boots, altitude sickness and tea houses, but only one of those is what the page is about. Salience is an attempt to answer that automatically.
It is worked out from position and pattern rather than from counting. A thing named in the title, in the opening lines and in the headings, referred to repeatedly, and surrounded by the words that usually accompany it, reads as central. A thing mentioned once in a closing aside does not, however important it might be in the world.
You can watch the idea in action. Google’s Natural Language API returns a salience value for each entity it finds in a piece of text, and running two drafts through it shows quickly which one is genuinely about the subject you intended.
Why entity salience matters
It is a decent proxy for a question you cannot easily answer about your own writing: is this page clearly about one thing? Pages that drift — a service page spending half its length on company history, a guide that keeps wandering into a related product — read as unfocused to people and score as unfocused to a machine.
It also explains a common frustration. Two pages on a site can both mention the same topic and neither ranks, because neither is obviously the page about it. Sharpening one and letting the other refer to it usually beats improving both.
Where entity salience goes wrong
Treating it as a target is the main risk. Salience scores come from a language tool, not from Google’s ranking systems, and pushing a number up by repeating a name is the modern version of keyword stuffing. The score is diagnostic — a way to check a draft against its brief — not a dial to turn.
The other error is confusing salience with importance. A page can be squarely about a subject and still be useless, and a low score does not always mean something is wrong; a comparison page genuinely covers two or three things evenly, and that is the correct shape for it.
How to act on it
Decide the one thing each page is about before you write, then put it where prominence is measured anyway: the title, the first sentence, the headings, and the natural repetitions in between. Name it in full rather than sliding into vague pronouns, especially anywhere a second subject has just been introduced.
Then cut. Most pages that fail this test fail because they contain a section that belongs on a different page. Move it there, link the two together, and both get clearer — which is the discipline behind a well-built topic cluster. If you want a check rather than a guess, run the draft through a language API, or simply ask someone to read it and tell you what it was about. The two answers agree more often than you would expect.