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Cookies and local storage: what a website can keep in the browser

Editorial illustration supporting the article: Cookies and local storage: what a website can keep in the browser
Visual guide for Cookies and local storage: what a website can keep in the browser. Illustration by Srithongkwao Knowledge Center.

Websites can store small pieces of data in the browser for sessions, preferences and technical operation. Not every stored item is an advertising cookie.

Srithongkwao Editorial TeamPublished 20 September 2026Reviewed 21 September 2026
In this guide: Understand session cookies, preferences, local storage and why clearing browser data can change sign-in or saved settings.
Important context

User control: Session data keeps workflows together should be explained in plain language before a user is expected to make a privacy or permission choice. A permission can often be denied, limited or changed later through browser or Android settings.

Data-minimization principle: Cookies and local storage: what a website can keep in the browser should use only the information needed for the stated purpose. Users should avoid sharing secrets or unrelated personal information simply because a form, screenshot or upload makes it technically possible.

Session data keeps workflows together

A website may use cookies or similar mechanisms to maintain a signed-in or multi-step session.

Removing session data can sign a user out or reset an unfinished workflow.

Key concepts for Cookies and local storage: what a website can keep in the browser
Key concepts from this guide.

Preferences can stay locally

Language, theme or dismissed notices may be stored in the browser.

Local storage can improve convenience without requiring the value to be sent on every page request.

Key ideas from Cookies and local storage: what a website can keep in the browser
Key ideas from this guide.

Third-party services can add storage

Advertising, analytics or embedded services may create their own browser storage subject to configuration and consent.

Privacy policies should identify relevant third-party categories.

Clearing data has side effects

Removing site data can solve stale-state problems but can also delete saved preferences or sessions.

Users should know what they may need to set up again.

Practical guide for Cookies and local storage: what a website can keep in the browser
Practical points to use with this guide.

Browser controls are useful

Modern browsers provide site-level controls for cookies, permissions and stored data.

These controls give users an independent way to reset or restrict a site.

Common mistakes to avoid

Practical checklist for Cookies and local storage: what a website can keep in the browser
Practical checklist and takeaways.

Practical checklist

Frequently asked questions

Are cookies always for tracking?

No. They can support sessions, security and preferences as well as advertising or analytics.

What happens if I clear site data?

You may be signed out and lose locally stored preferences.

Can I control one website separately?

Modern browsers commonly provide per-site privacy and permission controls.

Editorial note: This page is part of the Srithongkwao Knowledge Center. We separate product guidance, belief-based interpretation and safety information so readers can understand both the useful context and the limits of each topic. See our Editorial Policy and Corrections Policy.