How could a tiny image file do all that campaign tracking? These pixel tags even had a cute name -- tracking cookies! • Cookie deletion: This is when people proactively clear cookies or use incognito windows to avoid interest-based targeting and tracking. • Cookie blocking: This is when consumers turn on third-party cookie and ad blockers or decide to limit ad tracking by adjusting the settings on their browsers and devices. • Ad blockers built into browsers: Several of the smaller market share browsers have added cookie blockers, which also block tracking cookies.

Source: Forbes December 22, 2017 12:22 UTC