How can we be sure of our online privacy, when products know our specific tastes? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.

Answer by Emile Contal, Co-Founder of Crossing Minds, on Quora:

Privacy is a blurry term when it comes to personal data on the internet. We seriously believe it is important to be more and more conscious about its implications at a both a personal level and as a society.

Privacy is the ability of an individual or group to seclude themselves, or information about themselves, and thereby express themselves selectively. The boundaries and content of what is considered private differ among cultures and individuals.

So the answer to this question is very simple: you can't 100% be sure of it.

However there is already a lot you can do to check and understand how your personal information is used.

  • First and foremost, read the privacy section of the terms and conditions. It sounds extremely obvious and absurdly boring, but those sections that 90% of the population don't scroll through contain most of the answers to this question. For instance by reading it is clearly stated that Facebook collects your data even outside Facebook, even if you don't have a Facebook account, about which websites or mobile app you visit, your location, etc., and sells this data to advertisers. If that this type of personal data exceeds your "privacy threshold", it will be very hard to protect yourself. Indeed to prevent Facebook from accessing and selling it, you would not only need to uninstall Facebook but more than half of your mobile applications. To make things worse, companies not always respect their own policies. That is why governments created regulations like GDPR and the upcoming CCPA. Always double-check which companies are compliant. For GDPR, you can look at the list of notable fines for instance.
  • Try to understand the business model of the company behind the product. It is important to have a clear understanding if and how a company makes money from a product and the data coming from it. This specific monetization will define the company's values and actions. Understanding the business model is a great tool to make the difference between a product collecting behavioral data in order to improve its user interface, versus selling personal data to advertisers, insurance companies, or other third parties. If the company is public, it's easy to find their quarterly report to their shareholders by web search.
  • Try to assess the security level of the system, remember, data breaches are direct privacy loss. It is hard to evaluate from the outside, but you can ask yourself a few questions. Do they use https everywhere? Has the company ever experienced security breaches? How many security engineers seem to work there? Sometimes you can also try by yourselves to see how much information you can get about someone out of a product, without any hack. Look directly at the source code for the web profile of someone (you can do that in any browser), you might be surprised at what you find...
  • Use available online privacy tools. These won't prevent most of the above points, but it's better than nothing. They attempt to hide your online identity such as cookies, your location or other information provided by your web browser. Going back to the original question, these tools make sense only if your goal is opting-out from personalized products or third-parties. On desktop for certain web browsers it's worth mentioning the Do Not Track setting and ad-blocking extensions like AdBlock and uBlock. Using a VPN or Tor may also help hiding some of your personal information, but we advice to stay away from free VPNs which are often operated by for-profit companies selling this personal data to third parties! Unfortunately these tools are usually limited to desktop computers and do not exist for mobile.

This question originally appeared on Quora - the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter and Facebook. More questions: