The anatomy of a link
https://yoursite.com/?ref=jane&campaign=spring
ref— the affiliate’s slug. Rename the parameter under Settings → Tracking ifrefcollides with something else on your site.campaign— optional, free text, recorded on the visit so the affiliate can tell which placement worked.
Any URL on your site accepts the parameters, so an affiliate can link to the product page rather than the home page. Deep links convert better and cost you nothing to support.
Pretty links
The plugin also answers /ref/jane, which is easier to read aloud and survives being retyped. Both forms record the same visit.
The cookie window
The default window is 30 days. Longer favours the affiliate, shorter favours you, and the honest way to pick is to look at how long your buyers actually take to decide — a considered purchase with a 7-day window pays affiliates for almost nothing.
Short links
Pro adds branded short links, so an affiliate can hand out yoursite.com/go/jane rather than a query string. They resolve on your domain, which means they keep working when a third-party shortener goes away or gets blocked.
What to tell an affiliate
Their portal shows their link and copies it to the clipboard in one click. Send them there rather than composing links by hand: a mistyped slug records a visit credited to nobody, and neither of you finds out until the month ends.