Cookies are small files that websites store on your computer to remember information about you
A cookie is a text file — usually just a few kilobytes — that a website saves to your device when you visit it. The website can then read that file on your next visit to remember who you are, what you were doing, or what you prefer. Cookies are not programs and cannot run code or infect your device. They are just data: a username, a login token, a preference setting, or a tracking identifier.
Your browser stores cookies in a dedicated folder on your computer or phone. When you visit a website, your browser automatically sends the relevant cookies back to that site. The website reads them and uses the information to customize your experience — keeping you logged in, remembering items in your shopping cart, or showing you ads based on your browsing history.
Cookies are not inherently dangerous, but they do create a trade-off: they make websites more convenient for you, but they also let websites and advertisers track your behavior across the internet. Understanding what cookies do, which ones you need, and which ones you can refuse is the foundation of making informed choices about your privacy online.
Key Takeaways
- Cookies are text files that websites store on your device to remember information about you between visits.
- First-party cookies come from the website you are visiting; third-party cookies come from advertisers or analytics companies and track you across multiple sites.
- You can delete cookies at any time through your browser settings, and you can set your browser to refuse certain types of cookies or ask before accepting them.
- Some cookies are necessary for websites to function (like login tokens), while others exist purely to track your behavior for advertising purposes.
- Clearing cookies regularly is a straightforward privacy practice, though it means you will need to log back into websites and lose saved preferences.
First-party cookies versus third-party cookies
A first-party cookie is set by the website you are actually visiting. When you log into your email, the email service sets a cookie that keeps you logged in. When you add items to a shopping cart, the store sets a cookie that remembers what you picked. These cookies are necessary for the website to work the way you expect.
A third-party cookie is set by a different company — usually an advertiser or analytics service — embedded in the website you are visiting. You might visit a news site, and an advertising network sets a cookie on your device. That same advertising network has cookies on hundreds of other websites you visit. Over time, the network builds a profile of your browsing habits across all those sites and uses it to show you targeted ads.
Third-party cookies are the main reason websites can track you across the internet. A first-party cookie only tells one website about your behavior on that site. A third-party cookie tells an advertising company about your behavior everywhere. This is why privacy advocates focus on limiting third-party cookies — they are the mechanism that turns your browsing into a trackable profile.
What information do cookies actually contain
Cookies contain only the information that the website or advertiser explicitly puts into them. A login cookie might contain your username and a token that proves you are logged in. A preference cookie might contain your language choice or your preferred page layout. A tracking cookie might contain a unique identifier that links you to a profile somewhere on an advertiser's server.
Cookies cannot contain your password, your credit card number, or any information you did not provide to the website. They also cannot read information from your device beyond what you have already shared with that website. A cookie set by a news site cannot see your files or your email. It can only see what you did on that news site.
However, cookies can be combined with other data to build a detailed picture of you. If you visit a shopping site while logged in, the site knows your real identity and what you browsed. If you then visit other sites with the same advertiser's tracking cookie, the advertiser can connect your shopping behavior to your other browsing. This is why cookies matter for privacy even though they are just small text files.
How to see and delete cookies in your browser
Every major browser lets you view, search, and delete cookies. In Chrome, go to Settings, then Privacy and Security, then Cookies and Other Site Data. You will see a list of every website that has set cookies on your device. You can delete all cookies at once, or delete cookies from specific websites.
In Firefox, go to Settings, then Privacy and Security, scroll to Cookies and Site Data, and click Manage Data. You will see the same list. In Safari on Mac, go to Preferences, then Privacy, then Manage Website Data. On iPhone or iPad, go to Settings, then Safari, then Clear History and Website Data.
Deleting cookies will log you out of websites and erase saved preferences like your language choice or login information. You will need to log back in the next time you visit. This is the trade-off: clearing cookies improves your privacy, but it makes websites less convenient. Many people clear cookies once a month or when they are done using a shared device.
How to control which cookies you accept
You can set your browser to refuse all cookies, but this will break many websites — you will not be able to stay logged in, and some sites will not load properly. A better approach is to refuse third-party cookies while allowing first-party cookies.
In Chrome, go to Settings, then Privacy and Security, then Cookies and Other Site Data, and select "Block third-party cookies." In Firefox, go to Settings, then Privacy and Security, scroll to Enhanced Tracking Protection, and select "Strict." In Safari, go to Preferences, then Privacy, and check "Prevent cross-site tracking."
You can also set your browser to ask you before accepting cookies. In Chrome, select "Block third-party cookies in Incognito" or use Incognito mode for private browsing. In Firefox, you can set a custom cookie policy under Enhanced Tracking Protection. These settings vary by browser version, so if you cannot find them, search your browser's help documentation for "cookie settings."
The difference between cookies and tracking pixels
A tracking pixel is a different technology that serves the same purpose as a third-party cookie. It is a tiny, invisible image (usually 1 pixel by 1 pixel) embedded in a website or email. When you load the page or open the email, your browser downloads the image, and the server that hosts it logs your visit. The server can see your IP address and the time you visited, and it can link that visit to a cookie it set earlier.
Tracking pixels are harder to block than cookies because they look like normal images. However, if you disable images in your email client or use a privacy-focused browser, you can prevent pixels from loading. Some email services, like Gmail, block tracking pixels by default.
The key difference is that cookies are stored on your device and sent back to the server, while pixels are just images that log your visit when you load them. Both serve the same advertising and tracking purpose, and both can be limited through browser settings and privacy tools.
Why websites ask for cookie consent
In the European Union, the ePrivacy Directive requires websites to ask for your consent before setting non-essential cookies. This is why you see cookie banners on many websites, especially if you are visiting from Europe or the website serves European visitors. The banner usually offers options to accept all cookies, reject all cookies, or customize which types you allow.
In the United States, there is no federal law requiring cookie consent, though some states like California have privacy laws that give you rights to know what data is collected and to request deletion. Many websites show cookie banners anyway because it is simpler to use the same banner globally than to detect where a visitor is located.
Cookie banners are often designed to make accepting all cookies the easiest option — the "Accept All" button is large and prominent, while "Reject All" is small or hidden. If you want to limit tracking, look for a "Customize" or "Manage Preferences" button that lets you refuse third-party cookies while accepting first-party ones.
Frequently Asked Questions
Can cookies steal my passwords or credit card numbers?
No. Cookies can only contain information that the website explicitly puts into them. They cannot read your files, your passwords, or your credit card number. However, if a website is hacked, the attacker could potentially read the cookies stored on your device, which is why you should never save passwords in your browser and should use a password manager instead.
What happens if I delete all my cookies?
You will be logged out of every website, and websites will lose any saved preferences like your language or theme choice. You will need to log back in the next time you visit. Deleting cookies does not harm your device or your data — it only affects how websites recognize you on your next visit.
Do I need to delete cookies regularly?
It depends on your privacy preferences. If you are concerned about tracking, clearing cookies monthly or when you finish browsing is a straightforward practice. If you do not mind targeted ads and prefer the convenience of staying logged in, you can leave cookies alone. The choice is yours based on your own risk tolerance.
Why do some websites not work after I block third-party cookies?
Some websites use third-party services for features like chat support, video players, or payment processing. Blocking third-party cookies can break these features. If a website does not work, you can add it to your browser's exception list to allow third-party cookies just for that site, or you can temporarily disable your cookie restrictions.
Are cookies the same as browser history?
No. Browser history is a record of the websites you visited, stored on your device. Cookies are files that websites store on your device to remember information about you. You can delete both separately. Deleting history does not delete cookies, and deleting cookies does not delete history.