Cookies are temporary session identifiers stored locally on your browser. They allow connecting securely to the websites you browse every day and remember your preferences or favorite pages you follow.
Famous examples include Google Analytics, Facebook Pixel, LinkedIn Insight Tag, and Adobe Analytics.
Cookies also contain browser fingerprints such as the browser and the operating system you use.
Social media networks use various types of cookies for advertising and authentication purposes.
You must have seen those cookie alerts inviting you to accept cookies in your browser:
Here, TexAu uses Linkedin cookies to connect to your LinkedIn account, for instance.