What is Cookies?
Small text files that websites store on your device. Cookies can remember login state, preferences, or shopping carts (first-party) — or track you across sites for advertising (third-party). They're one of the primary ways you're followed online.
Also known as: HTTP cookies, Web cookies
Cookies were invented for legitimate purposes—remembering you between visits. They've since become the backbone of cross-site tracking.
Cookie Types
First-Party Cookies
- Set by the site you're visiting
- Remember login, preferences, cart
- Generally necessary for site function
- Same-origin policy limits their scope
Third-Party Cookies
- Set by domains other than the site you're visiting
- Ad networks, analytics, social widgets
- Track you across thousands of sites
- Being phased out by browsers (Chrome 2024+)
Session vs. Persistent
- Session: Deleted when you close the browser
- Persistent: Expire at a set date or when you delete them
Privacy Implications
- Tracking cookies: Build detailed profiles of your interests and behavior
- Authentication cookies: If stolen, attacker gets your session
- Consent: GDPR/CCPA require consent for non-essential cookies
- Cookie walls: "Accept or leave" — legally questionable in some jurisdictions
Protecting Yourself
- Browser cookie settings (block third-party)
- Privacy extensions (uBlock Origin, Privacy Badger)
- Private/incognito mode (cookies cleared when closed)
- Cookie consent tools often still allow tracking—read carefully
Related Terms
Browser Fingerprinting
A tracking technique that collects information about your browser, device, and settings to create a unique identifier. Unlike cookies, fingerprints are nearly impossible to delete and can track you across websites without your knowledge or consent.
Third-Party Cookie Deprecation
The industry-wide shift away from third-party tracking cookies — already blocked by Safari and Firefox, and being phased out in Chrome — that is reshaping online advertising, forcing the ad tech industry to find new ways to track users across the web.
Tracking
The collection and correlation of data about your behavior across devices, sites, and time. Tracking enables targeted advertising, analytics, and surveillance. It's how companies and data brokers build detailed profiles of who you are and what you do.
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