What Are Cookies, and How Do They Work?

A cookie is a small bit of information that a website stores on your computer. When you revisit the website, your browser sends the information back to the site. Usually a cookie is designed to remember and tell a website some useful information about you. For example, an online bookstore might use a persistent cookie to record the authors and titles of books you have ordered. When you return to the online bookstore, your browser lets the bookstore’s site read the cookie. The site might then compile a list of books by the same authors, or books on related topics, and show you that list.

This activity is invisible to you. Unless you have set your preferences so that you will be alerted when a cookie is being stored on your computer, you won’t know about it. When you return to a website, you won’t know that a cookie is being read. From your point of view, in the example above, you’d simply visit the online bookstore, and a list of books that might be of interest to you would magically appear.

Are there different kinds of cookies?

Yes, there are two commonly known types of cookies. One is called a “session” or “non-persistent cookie.” It is a cookie that only lasts as long as your session on the website and expires as soon as you leave. It is used to facilitate your activities within that site. For example, if you are shopping on an e-commerce site, this cookie enables their server to remember the items you are purchasing as you move about within the site. These are very common in many websites, as they are a standard part of Microsoft’s Active Server Page environment, an industry standard Web tool.

The second type of cookie, called a “persistent cookie” is so called because it persists beyond the life of your session and may live for months or years. A persistent cookie is created in order to recognize a user when they return to a website. It enables the site to offer a customized experience tailored to that user – such as remembering your name and password on protected login pages.

Can Cookies Be Used to Give My Information to Unauthorized People?

Cookies are usually harmless. They can’t be used to gather information about you (unless you provide it). But some services do use cookies to create a profile of your interests based on the sites you visit and the things you do there. Advertisers on participating sites can then tailor online advertising to your interests and buying habits. When in doubt, always check a website’s privacy policy.