What Is a Sales Page?
A sales page is a landing page built to move a visitor toward purchasing an offer.
What it must answer
What is the offer, who is it for, why does it matter, what is included, what proof supports it and what happens after purchase?
Length
Length should follow complexity. A simple low-risk purchase may need little copy; an expensive unfamiliar offer usually needs more explanation.
Checkout flow
Keep the transition from sales page to checkout consistent in offer, price and expectations.
Measurement
Track purchase conversion and downstream outcomes, not only button clicks.