You just bought what, Facebook knows right away, why is that?

Many users on Twitter and Reddit have reflected on the situation, as soon as the user has just purchased online or in a traditional store, Facebook immediately displays ads for similar products.

According to Business Insider, Facebook works with retailers to collect information about users' transactions both online and in stores. This data mining activity has been implemented since August 2019 and is called "off Facebook activity, off - Facebook Activity." This advertising tool is being deployed globally by Facebook and provided to partner on the platform to show targeted ads based on what the user wants.

According to Facebook, before matching the Facebook account, the data of the user's transactions were encrypted. This means that Facebook does not store a user's transaction history but only keeps a list of retailers "matching" with the user account.

To understand the data-based advertising tool outside of Facebook, let's learn about its operating process.

This process begins when the user purchases a product. Retailers will retain information about users and transactions.

This information will be sent to Facebook if the retailer cooperates with Facebook to advertise. The information sent includes name, phone number, province, country, gender, age, email address, etc. From that information, Facebook will create a "custom audience" or a defined group of users. Dinh was shopping there.

After being encrypted using a "hash", those data will be uploaded to Facebook. When the system matches users with other specific retailers, that data is deleted. The rest is just match data between users and retailers that match the products they sell.

Based on that, Facebook partners will display ads directly to a defined group of users.

In the US, many retailers have used advertising tools based on user activity data outside of Facebook to pull buyers back and expand the range of new customers.

Users can choose to agree or refuse to monitor activity outside of Facebook. To refuse, users access to Settings -> select "Ads" -> disable the option "Ads based on data from partners".

Users can also check themselves why targeted ads by clicking the arrow in the right corner of the ad post -> select: "Why do I see this ad?".

Advertising contributes greatly to the revenue of the world's largest social networking platform. With a huge demographic database, Facebook can provide partners with hyper-targeted ads. In the third quarter of 2019, advertising brought Facebook $ 17.3 billion.

1. Facebook Viewpoints - New Facebook application, paid survey participants
2. Warning: New malware can hijack Vietnamese users' access to Facebook and Gmail