Your digital footprint is basically the trail of breadcrumbs you leave behind...

https://seo.edu.rs/blog/active-vs-passive-digital-footprints-understanding-how-youre-being-tracked-11056

Your digital footprint is basically the trail of breadcrumbs you leave behind whenever you browse, shop, or use apps. Advertisers use these pieces of your history to build a profile and target you across the web