Susan Mathews was browsing online for bags and found one she liked but abandoned her search when her phone rang. Later that day, she saw an advert for the same bag she had looked at earlier, which was an example of personalized retargeting. This technique sends users ads for specific products they have viewed online and companies have been tracking users for years to target ads, but some users feel uncomfortable being constantly tracked and want more regulation of digital advertising. While personalized retargeting lets companies encourage purchases, experts say they shouldn't make users feel like they're being watched all the time.