A page with one purpose.
WHAT IT IS
A page built for one specific purpose, usually where advertising or a campaign sends people.
HOW IT DIFFERS FROM AN ORDINARY PAGE
One action, not several No competing navigation Content matched to what brought the visitor
WHEN TO USE ONE
For advertising campaigns For a specific offer For a single service you promote separately
WHEN NOT TO
For ordinary site pages, which serve several purposes
WHAT IT CONTAINS
A headline matching what brought them What the offer is Why it matters Evidence The action
WHAT IT DOES NOT CONTAIN
Full site navigation Links leading away Anything unrelated
WHY REMOVE NAVIGATION
Every link is a way to leave without acting.
WHAT TO MEASURE
Conversion rate for that page specifically.
That is the whole point of building it separately.