Meta Tag

A meta tag is an element in the head of an HTML page that states something about the document without displaying anything: its character encoding, a one-line description, or an instruction to a crawler. Each tag is a name paired with a value, and what the value does depends entirely on which program reads it.

How the element is built

Per the HTML standard, a meta element carries one of four things: a name, an http-equiv pragma, a charset declaration, or an itemprop for microdata. Exactly one of them. When it carries a name it must also carry content, and the pair is read as a name and a value. The standard defines a short list of names, among them description, author, application-name, generator, keywords, referrer, theme-color and color-scheme. Anyone may invent further names; whether anything acts on them is a separate question.

Which tags a search engine acts on

Google’s list of the meta tags it supports is short: description, robots and googlebot, viewport, google-site-verification, rating, notranslate, nopagereadaloud, refresh, and the charset. The same page says the keywords meta tag has no effect. So the tag most people think of first is the one that does the least.

The robots family matters more than it used to. Google’s documentation on AI features in Search says the preview controls already in use, noindex, nosnippet, max-snippet and the data-nosnippet attribute, apply to AI Overviews and AI Mode as well. A max-snippet set low enough to protect a page from being excerpted also stops it being quoted in an AI answer.

What a meta tag cannot do

A meta description is a suggestion for how the page is summarized in a list. It is not the passage an assistant lifts as an answer; that comes from the body. A page whose description is precise and whose body never states the fact in one place has described an answer it does not contain. Write the description last, from a sentence that is already on the page.

A common question

Can a meta tag keep a page from being quoted inside an AI answer?

One family can. Google's documentation on AI features in Search says the preview controls already in use, noindex, nosnippet, max-snippet and the data-nosnippet attribute, apply to AI Overviews and AI Mode as well, so a max-snippet set low enough to keep a page out of an excerpt also keeps it out of a generated answer. Most other tags do far less; the keywords tag, the one people reach for first, has no effect at all.

Sources

Element definition and standard names: the HTML standard. Supported and ignored tags: Google’s list of the meta tags it supports. Preview controls and AI features: Google’s documentation on AI features in Search.