Blog

You’ve seen the banners, clicked “Accept All,” and moved on. But what are cookies actually doing under the hood, and should you care?

If you’ve used the web for more than five minutes, you’ve encountered a cookie consent banner. They’re a fixture of the modern internet, right up there with password reset emails and “Subscribe to our newsletter” popups. But most people click through without really knowing what they’re agreeing to.

That’s a gap worth closing. Cookies are one of the most fundamental technologies in how the web works, and understanding them takes about as long as it takes to brew a cup of coffee. So let’s get into it.

The basic idea: remembering you

At their core, cookies are small text files that a website stores on your device through your browser. They were invented in 1994 by Netscape engineer Lou Montulli to solve a practical problem: the web is stateless.

What does “stateless” mean? It means that every time your browser requests a page from a server, the server has no memory of you. You could log in, click to a new page, and the server would treat you as a total stranger. That’s obviously not how we expect websites to work today.

Think of a cookie like a coat-check ticket. The website hands you a small piece of information (“your number is 42”), and every time you come back, you show that ticket so the server knows it’s still you.

Cookies solve the statefulness problem by giving the browser a tiny piece of data to hold onto and send back on every subsequent request. The server reads it and says, “Ah, this is the person who logged in earlier. They have a shopping cart with three items.”

What a cookie actually looks like

Despite their outsized role in web privacy debates, cookies are remarkably simple data structures. Each one is essentially a key-value pair with some metadata attached. A stripped-down example might look like this:

session_id=abc123; Expires=Thu, 27 Mar 2026 23:59:59 GMT; Secure; HttpOnly

That’s it. A name, a value, an expiration date, and a couple of flags. The browser stores this, and on every future request to the same domain, it includes the cookie in the request headers. The server can read it, update it, or delete it as needed.

The four main types

Not all cookies are created equal. They vary in lifespan, origin, and purpose. Here’s a quick breakdown of the kinds you’re most likely to encounter:

• Session cookies – Temporary. Erased the moment you close your browser tab. Used to keep you logged in during a single visit.
• Persistent cookies – Survive browser restarts. Responsible for “remember me” checkboxes and saved preferences.
• Third-party cookies – Set by a domain other than the site you’re visiting. Mostly used by advertisers to track behavior across sites.
• HttpOnly cookies – Invisible to JavaScript on the page. A security feature that protects sensitive tokens from certain attack types.

The legitimate uses (and the not-so-legitimate ones)

Cookies power a lot of things we take for granted. When you log into a service and don’t have to log in again the next day, that’s a cookie. When your shopping cart persists between visits, that’s a cookie. When a site remembers your language preference, your dark mode setting, or that you already dismissed a promotional banner, those are all cookies doing their job.

The controversy mostly surrounds third-party cookies and the advertising ecosystem built on top of them. A tracker embedded on thousands of websites can stitch together a detailed picture of your browsing behavior across the internet, all through the humble mechanism of a shared cookie. That’s the practice that triggered the wave of privacy legislation, including GDPR in Europe and CCPA in California, that resulted in all those consent banners we collectively find so annoying.

The end of third-party cookies

The advertising industry is in the middle of a significant transition. Firefox and Safari have blocked third-party cookies by default for years. Google, after several delays, has been rolling out restrictions in Chrome as well. The old cross-site tracking model is gradually giving way to new approaches that attempt to enable interest-based advertising without individual-level surveillance.

For most users, this shift will be largely invisible. First-party cookies, the kind that a site sets for itself to remember you, aren’t going anywhere. The web will continue to remember your logins and preferences just fine.

What you can do

If you want more control over which cookies live on your device, every major browser has a dedicated section in its settings where you can view, search, and delete them. You can also set browsers to clear cookies automatically when a session ends, or use private/incognito mode for sessions you’d rather not have remembered.

The cookie consent banners, annoying as they are, do give you meaningful choices if you bother to click “Manage preferences” rather than “Accept all.” Rejecting non-essential cookies limits what third parties can track, though it rarely affects a site’s core functionality.

Cookies are not inherently a privacy threat. They’re a tool, and like most tools, their impact depends entirely on how they’re used. Knowing the difference between a session cookie keeping your login alive and a third-party tracker following you around the internet is the kind of knowledge that makes you a more informed user, even if you still end up clicking “Accept all” nine times out of ten.