Don’t look now, but you’re being shadowed. It sure seems like it sometimes. Play around on social media, and ads start showing up a few minutes later for the discussions you just posted. Search a topic, click on a link, peek at an ad and, hey, are you being followed?

Read “Buyer Aware” by Marta L. Tellado and bet on it.

It’s almost quite scary: Online giants like the “Big Four – Amazon, Apple, Facebook and Google” – know what you’re doing this weekend. They know about your health concerns and your vacation plans, too, and they’re not alone, Tellado says.

Consumer products, financial firms and internet trolls also wreak havoc on your life. And you willingly let them.

“At some point early in the internet revolution,” Tellado says, “we lost control over our digital lives.”

She cites problems with Amazon devices that listened to a user’s conversation and sent it to a third party. A Facebook algorithm suggested a bigamist’s wives become friends. Millions of people innocently going about their lives are monitored and recorded on Ring devices, and the footage is easily accessible by police without a warrant.

Tellado points out the “ever-shrinking word ‘Ad’ in the corner of your Google Search...” She wonders why personal data is taken and sold and why isn’t “opting out” the default?

There are a few things that we, as consumers, can do:

• “The first is to be skeptical.” Reviews are faked all too often these days, and certain news outlets are “entertainment” and not news.

• Confirm before sharing on social media, to avoid passing on misinformation.

• Keep an eye on your elders; elder fraud is big business now.

• Watch your credit report carefully.

• Know how to opt out of data-collecting as much as you can and don’t let data breaches go unrepaired.

• Take security practices seriously and be “smarter” about navigating the internet.

• And “pester lawmakers by phone, email, or visits to stick up for consumers... we can do it state by stare if Congress dawdles.”

Once upon a time, when the internet was an infant, it was perceived as a benevolent place for knowledge. “Buyer Aware” makes it abundantly clear that the opposite is true.

Focusing on Big Business, the author and Consumer Reports CEO writes about some of the breaches of trust that the “Big Four” have broken, and it’s information that rivals anything a horror novelist could offer. These are facts that should keep your finger hovering over your mouse or keypad for a few extra think-about-it seconds before clicking.

Then again, don’t we already know what we’re giving up? While this information is great to have together, it’s nothing new. In reading about it in one single, thorough book, readers could be forgiven for wondering if fighting data collection and internet misusage is like a flea battling an elephant.

What’s here is encouraging and discouraging, both at the same time, but it’s necessary to know. Indeed, if you’re willing to do the work, “Buyer Aware” sheds good light on the internet shadows.

Terri Schlichenmeyer’s reviews of business books are read in more than 260 publications in the U.S. and Canada.