Have you ever wonder why powerful tools like Google Search, Gmail, Facebook, X, Tiktok, etc are all free to use ?

When you see they sell nothing, then you are what to be sold !

Advertisement is the main source of revenue that keeps many online tools and services free today. Advertising itself is not necessarily a bad thing. When it provides useful information proactively, it can save us time and effort by helping us discover products, services, and market options without having to research everything ourselves.

However, this indirect form of advertising also creates a serious problem: we often cannot know who is actually behind an advertisement. In fact, this has become an ideal channel for scammers to reach and manipulate users, particularly through social media platforms.

Many students and older adults have fallen victim to online scams because they may have less knowledge or experience navigating the digital environment. At the same time, as more companies experience system intrusions, hacking, and data theft, the personal information of millions of users can be exposed or leaked globally. When these problems come together: targeted advertising, anonymous advertisers, online scams, and large-scale data breaches, they create a serious threat to our privacy and digital security.

This post reveals some methods around online advertising industry found on Facebook and the same also can be applied in every social networks as well.

1. How can anyone make you read what they want you to read while using Facebook ?

Given that almost all of us use banking and non-banking applications, we regularly hear news about companies behind these applications being hacked, with users’ personal data leaked and sold on the dark web.

The dark web consists of websites and online services that operate with a high degree of anonymity and are frequently used for illegal activities. One of the most common is the sale of stolen or leaked data. Today, criminals can purchase leaked personal information using cryptocurrencies such as Bitcoin or Ethereum, making it significantly harder to trace their identities and transactions.

Once someone obtains our name, phone number, email address, or even home address, they can use this information to find our social media profiles on platforms such as Facebook, Instagram, and X. They may then gather additional information about our interests, relationships, workplace, location, or daily activities.

With enough information, an attacker can even combine these details with targeted advertising. By purchasing an advertising campaign and providing information about a particular audience, they can use the platform’s advertising system to reach people who match specific characteristics.

This creates a concerning cycle: a data breach exposes our information → criminals collect and combine it → social media reveals more about us → advertising systems provide another channel to reach us.

The result is not simply a loss of data, but a growing risk to our privacy, safety, and ability to control who can reach us online.

2. How do Facebook’s Targeted Ads work ?

2.1 Custom Audiences

Facebook allows anyone to use phone numbers, emails, or names to directly target a specific user:

• Advertisers upload a list of customer data (CSV) to Facebook Ads Manager.
• Facebook matches the data (phone/email/name) with existing user accounts.
• Once matched, only those users in the list will see the ads.

This is the most direct method of delivering ads to a known individual.

2.2. Lookalike Audiences

Based on a seed audience (e.g., 100 users with names and emails), Facebook finds other users with similar behavior.

This is indirect targeting, used to expand reach to similar users even advertisers don’t know names or emails.

2.3. Geotargeting / Geofencing

Facebook allow anyone to use the user’s location (address or GPS) to limit where an ad appears. This usually being used by physical stores. If you ever notice when you pass by some stores, you more likely see their ads on news feed.

2.4. Interest, Demographic, and Behavioral Targeting

When no personal data is available, Facebook allows anyone to filter audiences by:

• Age, gender, region, job title
• Online behavior (e.g., searching for a laptop, following specific pages)
• Past engagement with posts, videos, or websites

This is an indirect ways but still get ads appear to us.

3. How to defend ?

By utilizing the methods described above, almost anyone, from legitimate advertisers to scammers, can place messages directly in front of us while we scroll through Facebook, YouTube, Instagram, and other social media platforms.

On one hand, social networks provide free tools that satisfy our natural desire to connect, communicate, and share with others. On the other hand, their advertising systems can turn our personal information and online behavior into valuable targeting data for anyone willing to pay.

Although most advertisements are legitimate and harmless, we should still share only what is necessary on social networks. The more personal information we expose, the easier it becomes for scammers to understand us, target us, and potentially manipulate us through carefully crafted advertisements.

Share wisely. Stay cautious. Protect your privacy.