Definition
Deep link
A deep link is an affiliate link pointing at an internal page — pricing, an article, a feature — rather than the homepage.
Example: yoursite.com/pricing?via=marie rather than yoursite.com/?via=marie. An affiliate who has just written a pricing comparison sends their reader to the pricing page, not to a homepage where they have to find on their own what they were just told about.
The gain is measurable and comes purely from the steps removed: every intermediate click between the promise and the page that keeps it costs a share of the visitors. Attribution itself is unchanged — same parameter, read by the same script.
One thing to check before offering deep links to your affiliates: that the tracking script is on every page of the site, not just the homepage. A deep link to an unequipped page sends a visitor who will never be tracked, and the affiliate has no way of understanding why their clicks earn nothing.
Related terms
Affiliate link
An affiliate link is a URL that identifies the affiliate who shared it, usually through a parameter such as ?via= or ?ref=.
Affiliate conversion rate
A program's conversion rate is the share of affiliate clicks that end in a sale. It means nothing until you say what counts as a conversion.
Attribution
Attribution is the rule that decides which affiliate a sale belongs to. Without it, a purchase preceded by three clicks belongs to no one — or to everyone.