From hakin9.org
Your digital footprint is the trail of data left behind from all your online activity. Anything you share or do online—whether visiting a website, making a purchase, or interacting on social media—contribute to your digital footprint.
Your digital footprint is essentially an online portrait of yourself, accumulating into a detailed record of where you’ve been, what data you’ve shared, and any traces you’ve left behind in the process. The more active you are online, the larger your digital footprint grows—and so do the associated security risks.
While much of the information that makes up your digital footprint is a result of information you intentionally shared online, like signing up for a newsletter or sharing photos on your social media accounts, there are less obvious types of data that contribute to your footprint as well. This data falls into two main categories: active and passive.