You’ve probably seen a dialogue box requesting that you enable cookies for a Web site. You may have wondered what cookies are and whether enabling them puts your computer – or your privacy – at risk. Though some people remain wary of cookies, they play in important role in how users interact with Web pages.
What are cookies?
Browser cookies (also called HTTP, Internet, or Web cookies) are small text files shared between a Web site and computer for the purpose of delivering a customized browsing experience. Often, the cookie contains only a user ID, so the site can “recognize” the visitor when he or she visits the site again.
On a news site, for example, a user might give their ZIP code for the page to offer local news and weather information each time he or she visits. Cookies might also track which stories a user has clicked in the past, to suggest new stories he or she might want to read. In many cases, cookies help Web pages display their most relevant content.
How do cookies work?
- A Web site’s server sends the user’s computer a cookie.
- The computer stores the cookie.
- The computer sends the cookie back to the site’s server each time the user visits the site, so the site can “recognize” a repeat visitor.
When the Web server knows you’ve visited a site before, it can display your personalized page (“Welcome, John!”); remember your account preferences; save items in your online shopping cart; and more. Without cookies, you couldn’t save login information or Web form content (like commonly used addresses or phone numbers) to save time. For sites you visit frequently, this could become a nuisance.
Are cookies dangerous?
The short answer is: usually not.
Cookies are simple text files, not programs, so they can’t execute code to install a virus or other malware on your computer. They also can’t view, alter, or transfer any information on the computer they’re stored on. Web servers only have access to the information they have placed on your computer, the data stored in the cookie itself. Usually, the string of numbers or letters contained in a cookie are only useful to the Web server that generated them (like a user ID unique to that site and visitor.)
Cookies can be used to store more personal information like a user’s name and address – but only if the user provides that information to the site. If you wouldn’t trust a site to store your information responsibly, it may be safest to avoid volunteering it in the first place.
Can I delete or disable cookies?
Yes. All major browsers allow users to control cookie usage. Check out guides for Internet Explorer, Chrome, Safari, and Firefox. Users may also choose to view pages in “private” windows that delete all cookies when the browsing session ends. This is called Incognito for Chrome; InPrivate for IE; and Private Browsing for Safari and Firefox.