What is an intervention in CRO?
An intervention is a change made to a page for a particular visitor at a particular moment — a hint, an answer to an objection, a reminder, a prompt. It differs from a permanent page change in being conditional: it appears because of what this visitor is doing, and for most visitors the correct intervention is none.
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What formats can an intervention take?
From least to most disruptive: an inline hint in the page, a block inserted into the content flow, a small corner card, a sticky bar, a mobile bottom sheet, and — at exit intent on desktop — a modal.
Inline hint
A quiet highlight within the existing page. The least intrusive format and the one that should fire most often.
Injected block
An objection answered, or a comparison offered, placed in the flow of the page where the question arose rather than on top of it.
Contextual card
A small card in a corner, for an answer that does not belong in the page body.
Sticky bar
Persistent and unobtrusive; the one interstitial format Google's guidance endorses by name.
Bottom sheet
The mobile-native alternative to a modal, sliding up from the bottom and dismissible with a gesture people already know.
Exit modal
Desktop only, at exit intent — when the session is ending anyway and the cost of interrupting is at its lowest. A modal over a phone screen is the format that gave this whole category its reputation.
When should an intervention fire?
Rarely. Most visitors need nothing — they are browsing, or have already decided, or were never going to convert — and interrupting someone who was already converting has a real cost.
Choosing the moment is most of the skill; choosing the message is the rest. The wrong intervention at the right moment is worse than silence, because it also spends the visitor's patience, and patience does not replenish within a session.
A useful discipline is a hard ceiling — at most one per page — which forces the system to rank its options rather than fire all of them and hope.
What may an intervention say?
Only what can be traced to a verifiable source: the site's own content, or a fact its owner stated. Anything else — a stock level, a delivery date, a review, a count of people viewing — is invention, and the plausibility of it is what makes it dangerous.
This is the constraint that separates a useful system from a liability, and it is architectural rather than editorial. A system that generates copy freely and is merely instructed to be truthful will eventually assert a guarantee nobody gave it, on a client's site, in the client's voice.
The test to apply to any such system: is the constraint a check the claim passes or fails, or a line in a prompt asking it politely?
See it on your own site
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