Some online shoppers in the Maritimes are wondering why items they’ve previously looked at online continue to show up as advertisements.

Computer security expert Dan Lirette says it’s a phenomenon called ad-tracking, where a company puts a small file in your computer via browser.

“(It) tracks where you go online, what you do, what you look at and what you buy,” said Lirette.

Networks like Facebook, Twitter and Amazon can use this information to generate ads you may be interested in, according to things you've browsed before.

“I can click on something and look at it and say, 'Nah, I don't want it,' and then a couple of days later, I'm getting emails from these people. I'm wondering, who are these people?” said online shopper Jim Buchanan.

Others are calling it a violation of privacy.

“Because they know what I'm looking at and they know my activity online,” said Claudette Mills.

While unnerving, Lirette says it's often more of an annoyance than a security risk.

“Advertisers track users and they sell that data. They make multiplied millions off of you browsing,” he said.

Lirette says programs like AdBlocker will stop these ads from showing up, but they don't stop your data from being collected. The best way to stop ad-tracking is to update your browser and download a secure extension for added privacy.

There is also an option to block third-party cookies under the advanced privacy settings in your web browser.

“The cookies, the tracking files that will get into your computer via, in layman's terms, holes, ports, channels, will be blocked by the extensions.

And while many don't like that it happens, they say ad-tracking won't deter them from shopping online.

“Everything you do online is gathering.Ssomebody is gathering information somewhere, so I know it's not a perfectly private thing to be on,” said Buchanan.

So while it can feel like big brother is looking over your shoulder, there is a way to reclaim your privacy when shopping online this holiday season.

With files from CTV Atlantic’s Cami Kepke.