Free Guide: Understanding Internet Cookies and Your Privacy

What Are Internet Cookies and How Do They Work?

Internet cookies are small text files that websites store on your computer or mobile device. When you visit a website, the site can create a cookie and save information in it. This cookie then stays on your device, and the website can read it when you visit again.

Think of cookies like a notebook that a store keeps about your visits. When you go to a store repeatedly, the staff might remember what you like to buy, what size clothes you wear, or that you always pay by credit card. Cookies work similarly—they store information about your browsing habits, preferences, and activities on websites.

There are different types of cookies that work in different ways. First-party cookies are created by the website you're visiting directly. If you go to a news website and it sets a cookie to remember that you prefer articles about sports, that's a first-party cookie. Third-party cookies are created by other companies, often advertisers or data brokers. These cookies can track you across many different websites you visit.

Session cookies are temporary and disappear when you close your web browser. If you're shopping online and put items in your cart, a session cookie remembers what's in your cart while you're shopping. Once you close your browser, the cookie is deleted. Persistent cookies stay on your device for a set period of time, sometimes for years. These allow websites to remember you the next time you visit, even weeks or months later.

Cookies work through a simple technical process. When your browser requests a webpage, the website's server sends back the webpage along with instructions to create a cookie. Your browser stores this cookie. The next time you visit that site, your browser automatically sends the cookie back to the server. The server reads the cookie and uses the information in it to customize your experience—such as showing you products similar to ones you looked at before.

Practical takeaway: Cookies are files that track your online activity and preferences. Understanding what they are helps you make informed decisions about your digital privacy. You can see what cookies are on your device by looking in your browser settings, though most people never bother to check.

Why Websites Use Cookies

Websites use cookies for many reasons, and not all of them are concerning. Some cookie uses are practical and make your browsing experience better. Other uses raise privacy questions. Understanding why websites use cookies can help you decide what level of cookie use you're comfortable with.

One major reason websites use cookies is to remember your login information. When you log into your email account, social media profile, or online banking site, a cookie stores proof that you're logged in. This means you don't have to enter your username and password every single time you visit a new page on that site. Without this type of cookie, online services would be frustrating to use. You'd have to authenticate yourself constantly. This is considered a legitimate and helpful use of cookies.

Shopping websites use cookies to maintain your shopping cart. When you add items to your cart on an online store, a cookie remembers what you've selected. You can continue browsing, leave the site, and come back later, and your items will still be there. Without this cookie, you'd lose your cart every time you navigated to a different page or closed your browser. E-commerce relies heavily on this functionality.

Websites also use cookies for analytics and understanding how people use their sites. Website owners want to know which pages are popular, how long visitors stay on the site, and what content keeps people interested. They use cookies and analytics tools to gather this data. This information helps them improve their websites and provide better content. Analytics cookies typically don't identify you personally—they just track general patterns of how many people visit and what they do.

Advertising is another major reason for cookies. Advertisers use cookies to track what products you view, what you search for, and what you click on. This information helps them show you advertisements that match your interests. For example, if you look at running shoes on several websites, you might then see running shoe ads when you visit other websites. This is called targeted or behavioral advertising. While it can feel like companies are watching you, it's actually cookies collecting and sharing this information. Many people find this practice invasive, even though it helps pay for the free content and services they use online.

Websites also use cookies to personalize your experience. News websites might use cookies to remember which topics interest you and show you more articles about those topics. Shopping sites use cookies to recommend products similar to ones you've looked at. This personalization makes websites more relevant to individual users.

Practical takeaway: Some cookie uses—like remembering your login or maintaining your shopping cart—genuinely improve your experience. Other uses, like tracking your behavior across websites for advertising, raise privacy concerns. Knowing the difference helps you decide which cookies to allow.

Privacy Concerns and Risks Associated with Cookies

While cookies have legitimate uses, they also pose real privacy risks. Understanding these risks helps you protect your personal information and make better decisions about your online privacy.

One major concern is behavioral tracking. Third-party cookies can follow you from website to website, creating a detailed profile of your online activities. Advertisers and data brokers build these profiles to understand your interests, habits, and preferences. Over time, they know a lot about you—what you search for, what you buy, what you read, and even your location if websites have that data. This information can be sold to other companies or used in ways you never intended. A person might not realize that their browsing history has been sold to dozens of different companies.

Data brokers—companies that specialize in collecting and selling personal information—use cookies to gather data at scale. They combine cookie data with other information they've purchased or obtained to build detailed profiles on millions of people. These profiles are then sold to marketers, insurance companies, employers, and other organizations. Someone might not realize that a data broker has information about their health concerns, financial situation, or shopping habits, and that this information has been sold to others.

Another risk is that cookies can be stolen or intercepted. If you use public Wi-Fi at a coffee shop or library, someone with the right technical skills could intercept the cookies being transmitted between your device and websites. They could then use those cookies to impersonate you or access your accounts. This is why security experts recommend not doing sensitive activities like banking on public Wi-Fi.

Cookies can also reveal sensitive information about your health, finances, or personal life. If you visit a medical website researching a disease, that information could be tracked by cookies and sold to insurance companies or employers. If you visit financial websites, that could be tracked and sold to lenders or investment companies. This creates opportunities for discrimination or misuse of sensitive personal information.

There's also the issue of transparency and consent. Many websites don't clearly explain what cookies they use or what they do with the data collected. Some websites use dark patterns—design tricks that make it hard to refuse cookies but easy to accept them. Users might think they're consenting to a simple tracking cookie when they're actually agreeing to their data being shared with dozens of companies.

Cookies can also lead to price discrimination. Some research suggests that companies might use cookies to track your shopping habits and show different prices to different people based on their willingness to pay. A person who frequently buys expensive products might see higher prices than someone who price-compares frequently. This raises ethical questions about fair pricing.

Practical takeaway: Cookies enable detailed tracking of your online behavior, which can be sold to third parties. Sensitive information—like medical or financial data—can be tracked through cookies. Protecting yourself means understanding what cookies do and taking steps to limit tracking.

Types of Cookies and What Information They Collect

Different cookies collect and use different types of information. Knowing what types exist and what they track helps you understand what's happening when you browse the internet.

Authentication cookies are used to keep you logged in to websites. These cookies store a session ID or token that proves to the website that you've already entered your login credentials. Without authentication cookies, you'd have to log in every time you click a link on a website. These cookies are generally considered necessary for websites to function properly, and most people accept them without hesitation. They typically don't raise major privacy concerns because they're used only by the website that created them and only while you're using that site.

Performance and analytics cookies collect information about how you use a website. They track which pages you visit, how long you stay on each page, what links you click, and if you encounter any errors. Website owners use this information to understand which content is popular and how to