Purchase attempt
A purchase attempt is a check in which an agent actually drives the store rather than reading it: it opens a product, chooses an option, adds it to the cart, opens the cart, starts checkout and goes as far as the payment step.
The attempt stops at the payment step and never submits payment. Reaching that step is what the test is for, and going further would mean putting a real order into a real merchant’s system. Ottom’s agents also identify themselves with a published user agent from static addresses, so a store owner can recognise the traffic.
Each of the six steps can fail on its own, and the step it failed at is the finding. That is the difference between a purchase attempt and any check that only reads pages: the failure is observed, not predicted.
Why it matters to a store
Signals tell you what a store publishes about itself. An attempt tells you what happens when something tries to buy. Stores pass the first and fail the second often enough that the gap is the reason this product exists.