A cookie is data that a website saves in your web browser. It helps the website store some details about your visit. For example, it may keep you signed in, save your language choice, or remember items in your shopping cart.
Cookies are also called ‘web cookies’ or ‘browser cookies’. They help websites work well because the web does not remember every visit by itself. However, some cookies are also used to study browsing patterns or show ads.
A cookie is a small piece of data that a server sends to your browser. The browser may store it and send it back with later requests to the same server (MDN Web Docs). You may also hear it called a browser cookie.
Why does this matter? A website does not remember you by default. Each page request begins fresh. Cookies resolve that problem.
Cookies are also small. Most browsers allow about 4 KB for each one, according to MDN. They hold short values, not big files.
For example, imagine you add a shirt to your shopping cart. You then open another page on the same store. A cookie may help the store remember the item in your cart.
Cookies have several purposes. Their role depends on how a website is built and what the site needs to remember.
After you sign in, the server gives your browser a cookie with a session ID. Your browser returns it on every page. As a result, you stay logged in. Shopping carts work the same way.
Cookies can store your language, theme, or region. For example, a news site can open in your language every time. Online stores can also remind you of items you viewed.
Cookies can record how you move through a site. Owners use this data to find weak pages and improve speed. Advertisers use this information to display ads that align with your interests.
Here is my view. Tracking is where most trust problems begin. The same technology that saves your cart can also follow you across the web. So the purpose of a cookie matters more than the cookie itself.
Some cookies help site owners learn how people use their pages. They may show which pages get visits, how users move through a site, or where a visitor leaves.
This data can help a site owner find pages that need work. However, the amount of data collected depends on the tools used and the site’s privacy settings.
Some cookies help ad services measure ad views or show ads based on browsing activity. For example, you may view a pair of shoes on one site and later see an ad for similar shoes.
This can help advertisers reach people who may like a product. Still, tracking across sites can raise privacy concerns.
You can sort cookies in three ways: by lifespan, by owner, and by purpose.
Session cookies: These keep you signed in while you browse. They are deleted when you close the browser.
Persistent cookies: These stay on your device for a set time. They remember your choices on future visits.
Persistent cookies do not last forever. Chrome limits them to 400 days from the day they are set, and this rule started in August 2022.
No single type is better than the others. The right mix depends on your goal. Also, all of these types can work together on one site.
You may have read that Chrome would block them. That story has changed. In July 2024, Google dropped its full phase out plan. In April 2025, it also dropped the idea of a choice prompt. By October 2025, it had retired the Privacy Sandbox tools meant to replace them.
As of now, Chrome still allows third party cookies by default. You can block them in your settings. Other browsers, such as Safari and Firefox, already limit many of them.
My advice is simple. Do not plan around one browser’s decision. Instead, build your site on first party data, such as accounts and email sign ups. That approach stays useful whatever happens next.
Most cookies are not harmful by themselves. They are small data records, not programs that install viruses on your device.
However, cookies can create privacy and security risks if they are used poorly. For example, a stolen sign in cookie may let someone misuse an active session.
Websites should use secure settings to reduce these risks.
For example, the Secure setting helps send a cookie only over an encrypted HTTPS connection. The HttpOnly setting helps stop page scripts from reading a cookie. The SameSite setting can limit when a browser sends it with requests from other sites.
You can also protect yourself by using an updated browser, avoiding suspicious links, and signing out on shared devices.
Cookies can be misused if they are not set up well:
Use all three for login cookies. It is a small change with a big payoff.
You can remove stored cookies through your browser settings. The exact steps depend on the browser and device.
In Google Chrome on a computer:
Review the options before you delete data. Removing cookies may sign you out of websites and reset saved preferences.
You can also manage third party cookies in Chrome’s privacy settings. Other browsers offer their own controls for cookies and tracking.
Also Read: Applications of Artificial Intelligence
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