Third-party Cookies
Third-party cookies are cookie files that are created by a domain other than the website the user is directly visiting.
They are used to track user behavior across different websites and are often employed in online advertising and analytics.
How Third-party Cookies Work
When a user visits a website, the browser may load elements not only from the main domain but also from third-party services, for example:
- Advertising networks;
- Analytics platforms;
- Social media widgets.
If such a service sets a cookie, it is considered a third-party cookie because it belongs to a different domain.
Example
- A user opens a news site.
- An advertising banner from an ad network is placed on the page.
- The browser loads the banner from the ad network’s server.
- The system sets a third-party cookie.
- This cookie allows the ad network to recognize the user on other websites where its advertising is placed.
This is how a user’s interest profile is built.
Why Third-party Cookies Are Used
Third-party cookies are used for:
- Targeted advertising;
- Retargeting;
- Analyzing user behavior across different websites;
- Measuring the effectiveness of advertising campaigns.
Limitations and Industry Changes
In recent years, the use of third-party cookies has become restricted due to privacy concerns and personal data protection.
Main reasons include:
- Data protection legislation (e.g., GDPR);
- Browser privacy settings;
- The gradual phase-out of support for third-party cookies by browsers.
In response, companies are seeking alternative methods for tracking and targeting, such as:
- First-party data (data collected by the website itself);
- Contextual advertising;
- User identifiers without cookies.
Key Takeaways
Third-party cookies are files set by external services to track users across different websites.
For a long time, they were an important tool for online advertising and analytics, but their use is now gradually declining due to privacy requirements and changes in browsers.
