Scott Meyer Scribe Media / YouTube Ghostery, one of the most popular ad-blocking services on the web, is owned by a company that uses the data it collects from its users to help advertisers target their ads better, the MIT Technology Review reports.

Ghostery is a widget users can install in their web browsers, and it's made by a company called Evidon. It blocks the tracking code that advertisers use to target you with ads, keeping your browsing private. MIT says:

Yet few of those who advocate Ghostery as a way to escape the clutches of the online ad industry realize that the company behind it, Evidon, is in fact part of that selfsame industry.

Evidon helps companies that want to improve their use of tracking code by selling them data collected from the 8 million Ghostery users who have enabled the tool's data sharing feature.

"This is not a scheme," MIT quotes Scott Meyer, Evidon's CEO, as saying. It's helpful to give advertisers Ghostery's data because advertisers don't generally want to target people who have opted out of advertising, he says.

It's no secret, either. Evidon was originally called "Better Advertising," as its own web site makes clear.