You wake up in the morning and, first thing, you open your weather app. You close that pesky ad that opens first and check the forecast. You like your weather app, which shows hourly weather forecasts for your location. And the app is free!

But do you know why it’s free? Look at the app’s privacy settings. You help keep it free by allowing it to collect your information, including:

This type of data collection is standard fare. The app company can use this to customize ads and content. The more customized and personalized an ad is, the more money it generates for the app owner. The owner might also sell your data to other companies.

You might also check a social media account like Instagram. The subtle price that you pay is, again, your data. Many “free” mobile apps gather information about you as you interact with them.

As an associate professor of electrical and computer engineering and a doctoral student in computer science, we follow the ways software collects information about people. Your data allows companies to learn about your habits and exploit them.

It’s no secret that social media and mobile applications collect information about you. Meta’s business model depends on it. The company, which operates Facebook, Instagram and WhatsApp, is worth US$1.48 trillion. Just under 98% of its profits come from advertising, which leverages user data from more than 7 billion monthly users.

Read more: How Internet of Things devices affect your privacy – even when they're not yours

Before mobile phones gained apps and social media became ubiquitous, companies conducted large-scale demographic surveys to assess how well a product performed and to get information about the best places to sell it. They used the information to create coarsely targeted ads that they placed on billboards, print ads and TV spots.

Mobile apps and social media platforms now let companies gather much more fine-grained information about people at a lower cost. Through apps and social media, people willingly trade personal information for convenience. In 2007 – a year after the introduction of targeted ads – Facebook made over $153 million, triple the previous year’s revenue. In the past 17 years, that number has increased by

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