The attribution window is the length of time between a user click and a conversion during which an affiliate or ad source can claim credit. Typical values: 7 days (DTC), 30 days (SaaS), 90 days (high-consideration B2B).
Shortening the window improves last-click advertiser economics; lengthening it rewards top-of-funnel partners. Every advertiser fight with their affiliate program eventually becomes a fight about the attribution window.