Digital Privacy: What Cookies Can’t Do in 2025

If you think a cookie can read your mind, you’re in for a reality check. Cookies are tiny text files that store data, but they have clear boundaries. Knowing those limits helps you stay safe and avoid costly mistakes.

Technical limits you should know

First off, cookies can’t run code on your device. They only store simple key‑value pairs, so they can’t install software or change system settings. That means a cookie can’t turn your computer into a hacker’s playground by itself.

Second, cookies live in a single browser. Open Chrome? The cookie you set there won’t follow you to Firefox. This siloed design stops one site from spying on what you do in another browser, unless you let it.

Third, size matters. Most browsers cap a cookie at 4 KB. Anything larger gets cut off, so cookies can’t hold massive data sets or detailed browsing histories. If you see a site claiming it stores “your entire life” in a cookie, it’s just marketing hype.

Legal rules that shape cookie use

In 2025 the GDPR still demands explicit consent for non‑essential cookies. You must see a clear opt‑in prompt, and you should be able to withdraw consent at any time. The California CPRA adds a similar layer, giving users the right to delete or limit the sharing of their data.

Australia’s Privacy Act treats cookies as personal information when they can identify an individual. That means you need a transparent privacy notice and a simple way for users to reject tracking cookies.

Across the board, the law says you can’t use cookies for:

• Collecting biometric data.
• Tracking a user after they’ve opted out.
• Sharing data with third parties without a clear purpose.

Breaking these rules can lead to hefty fines, so compliance isn’t optional.

So, what can you do today? Start with a quick cookie audit. List every cookie your site drops, note its purpose, and mark whether it’s essential. Then match each one against the GDPR, CPRA, and Australian guidelines. If a cookie doesn’t have a solid reason, remove it or make it optional.

Finally, give visitors a simple checklist: check the consent box, read the brief privacy note, and click ‘Accept’ only if they’re comfortable. This tiny step builds trust and keeps you on the right side of the law.

Understanding what cookies can’t do cuts through the noise and lets you focus on what really matters—protecting user data and staying compliant. Keep this guide handy, and you’ll navigate digital privacy with confidence.