A regular process of confirming orders by taking into account return period and other considerations like cancellations.
Validating sales is a really important part of running an affiliate programme as it links to how much and when an affiliate is going to be paid. Validation process should be transparent and be done as quickly as possible.
Example: A brand may have a 60 day return window, once that 60 days has passed a sale should be validated ASAP so payment can be made to the partner.
References: Adtraction