Tracking return on investment means checking if the money spent on ads brings more money back in sales. Affiliates usually use tracking tools that record each click, opt in, and purchase. Special tracking links are placed inside ads so the system knows where visitors came from. By comparing ad cost with commissions earned, the affiliate can see if the campaign is working. If costs rise higher than income changes are needed in the ad, audience, or landing page. This simple tracking habit guides better decisions. What methods are widely discussed?