Have you ever wondered how websites remember your preferences?
Like how Google knows your preferred language is Spanish, or how your favourite blog magically loads in dark mode, because you set it up that one time two years ago?
That happens because of cookies.
Cookies are directly tied to your online privacy as they store much more than your language and preferred theme.
This page should serve as your internet crash course on cookies: what they are, how they work, who uses them, and why you should care.
What Are Internet Cookies?
When you visit a website, it may store a small text file in your browser, usually containing data about you. This data is later used to identify you and remember your login status, language preferences, items in your shopping cart, and more. That text file is a cookie.
So, a cookie is like a name tag. It would probably say something like “Hi, I’m user #7593. I like dark mode. And keep me logged in.”
What Are Cookies Used For?
Cookies aren’t just random data dumped on your browser for no reason; they’re how the internet remembers you. Websites use cookies to make the user experience feel more personal, smooth, and consistent across multiple browsing sessions. But as with most things online, there’s a fine line between helpful and creepy, and cookies often cross that line.
Cookies are used for a few different things, and here are a few of them.
Keeping You Logged In
Ever close a tab and return later without having to log in again? That’s a cookie keeping your session active. It stores a unique ID so the website knows it’s still you without having to retype your login credentials.
Remembering What’s in Your Cart
E-commerce sites use cookies to remember your shopping cart, even if you bounce before checkout. Without cookies, your cart would vanish the moment you clicked away.
Saving Preferences
Whether it’s language settings, video autoplay toggles, or dark mode, cookies help sites recall your personal preferences so you don’t have to reset them every time.
Tracking Behaviour
This is where things get a bit more complex. Analytics cookies track how you use a site (e.g., which pages you visit, how long you stay, and what you click). It helps site owners improve content and user experience… in theory.
Personalised Advertising
Advertisers use cookies (especially third-party ones) to follow you around the internet. You look at a pair of headphones once, and now you’re seeing ads for them on every other site. Cookies are how that ad ecosystem knows what to show you.
So while some cookies are harmless and even helpful, others exist purely to track, profile, and monetise your attention. The more you know what they’re doing, the better control you’ll have over your browsing experience.
Why Should You Care About Cookies?
At first glance, cookies seem harmless. They remember your login, save your cart, and make your browsing experience smoother. But here’s the catch: not all cookies are there to help you. Some are just quietly watching.
Most websites don’t just use cookies for convenience. They also use them to collect data about what you click, where you go next, how long you stay, and what device you’re using. It’s all bundled up, sometimes shared or even sold, and used to build a digital profile on you, often without your explicit knowledge.
Still not convinced? Here’s why cookies matter:
They Track You Across the Web
That ad for cat food that followed you from your grocery delivery site to Instagram? That’s a cookie at work. It may have originated from a completely different site, but it’ll still track you across platforms, tabs, and time.
Your Data Gets Collected (and Monetised)
Every time a tracker learns more about you: what you like, when you browse, what device you’re on, that info gets added to your profile. Not necessarily by name, but enough to tailor ads, manipulate choices, or influence recommendations. Your attention is the product that’s being sold here.
Privacy Isn’t the Default
Most people never dig into cookie settings. Many just click “Accept All” and move on. That means you’re probably allowing a long list of companies you’ve never heard of to store data about your behaviour, often longer than you’d expect.
Security Risks (Though Rare)
In some cases, cookies can be exploited. If someone hijacks your session cookie, they could potentially impersonate your login session on another device. Not particularly common, but possible if you’re on an insecure network or an untrustworthy site.
So, to sum it up: cookies aren’t inherently bad. But they can be invasive if left unchecked. And the more you understand what they do, the better equipped you’ll be to decide who gets to follow your movements around the web, and who doesn’t.
What Are The Differences Between First-Party and Third-Party Cookies?
Not all cookies are out to get you. Some are just there to help the site you’re actually visiting function properly.
First-Party Cookies
These are cookies created and stored by the website you’re actively visiting. For example, if you log into your favourite news site, that site might use a first-party cookie to keep you logged in, remember your reading preferences, or save your language setting.
They’re generally harmless and often necessary for a good experience. Since the data stays with the site you’re using, the privacy risk is low.
Used for:
- Staying logged in
- Saving settings (e.g. dark mode, language)
- Keeping items in your shopping cart
Third-Party Cookies: The Sneaky Ones
Other domains set these, usually ad networks, social media widgets, or analytics platforms, that are embedded on the site you’re visiting. So even though you’re reading a blog, it might load cookies from Facebook, Google Ads, or dozens of unknown adtech companies.
These cookies follow you around the internet, collecting data to build a profile of you. They’re how you end up getting ads for a hotel you only looked at once, even on a completely different website.
Used for:
- Cross-site tracking
- Profiling
- Personalised ads and retargeting
How Do Third-Party Tracking Cookies Work?
Okay, so you’re on a website, let’s say… a recipe blog. You’re just there for the banana bread, but behind the scenes, things are happening. Not just between you and the blog, but between the blog and a bunch of other companies you didn’t sign up to meet.
A third-party cookie is set by a domain other than the one you’re visiting. So while the recipe blog is “first-party,” any cookie set by, say, Google, Facebook, or some unknown ad network is “third-party.”
These cookies are embedded through ads, like buttons, tracking pixels or scripts the site often uses for monetisation or analytics. And because these third-party trackers are on many sites, they can follow your activity across the web.
Here’s what really happens behind the scenes:
- You visit that recipe blog.
- The site loads a Facebook “Share” button or uses Google Analytics.
- When that element from Facebook or Google loads, it drops a cookie from its own domain.
- Now, Facebook or Google knows that you visited this page, at this time, from this device.
- You go to another site that also has a Facebook widget or Google ad? That same cookie is read again, adding more data to your profile.
- Over time, this builds a super detailed profile of your interests, habits, devices and even rough location. All without you ever logging in.
Why does this exist?
Because ads are a billion-dollar business, and personalisation drives clicks. The more an ad knows about you, the more likely it is to grab your attention. These cookies help ad platforms serve targeted ads, measure conversions and retarget you across the internet.
Why is this a problem?
It’s a problem because a lot of the time, you usually don’t know it’s happening. You never visited “ads.google.com,” yet it’s setting cookies, tracking you and learning about your behaviour just because you visited a site that uses it.
That’s why many browsers and privacy tools (e.g., ad blockers) are now cracking down on third-party cookies. They’re helpful for marketers, sure. But for regular users? They’re mostly noise, and a potential privacy nightmare.
What Can You Do About Cookies?
You’re not powerless here. While cookies are baked into how the internet works (pun fully intended), there’s plenty you can do to stay in control.
Block Third-Party Cookies
Most modern browsers let you block third-party cookies entirely, and that’s a great start if you value privacy. Chrome, Firefox, Safari, and Brave all have settings to block trackers from advertisers and unknown sites.
If you want an extra layer of protection, consider one of the best ad blockers of 2025. Many of them also block the scripts and trackers (alongside ads, of course) that try to set third-party cookies in the first place.
Clear Cookies Regularly
Cookies aren’t permanent. You can delete them anytime, and you probably should, especially if you’re switching devices, selling your laptop or just want to wipe the slate clean.
Every browser lets you do this, and it only takes a few clicks. If you don’t know where to start, we’ve got a step-by-step guide on how to clear cookies for every major browser.
Use Private or Incognito Mode
When you browse in private or incognito mode, your browser doesn’t save cookies after the session ends. It’s a quick and easy way to stop sites from tracking you between visits.
Use Privacy-Focused Browsers
Some browsers, like Brave or DuckDuckGo, are designed with tracking protection built in. Check out the best private browsers of 2025.
Say “No” to Cookie Pop-Ups (When You Can)
Cookie banners are everywhere now, and many of them are designed to make it easy to click “Accept All”. However, most sites are legally required to offer you the option to decline non-essential cookies. Look for a “Manage Settings” or “Decline All” button, and don’t let it fool you.
And if you run a website yourself, this applies to you as well. You’re responsible for how your site handles cookies and user data. If you’re trying to stay on the right side of data protection laws like GDPR or CCPA, and you don’t want to exploit your users’ data (good on you), make sure you’re using one of the best consent management platforms of 2025. These tools help you collect proper cookie consent, manage preferences, and stay compliant.
Frequently Asked Questions
Sort of. Accepting essential cookies (like the ones that keep you logged in or save your preferences) is generally safe and necessary for the site to work. But accepting all cookies means allowing third-party trackers to collect data about your activity, sometimes across multiple sites. So, safe? Mostly. Private? Not always.
When you decline cookies, most sites will stop setting non-essential ones, like trackers and ad pixels. The core functionality usually still works, but you may lose convenience features such as saved logins or site preferences. Some sites may also prompt you more frequently about cookie settings or display less relevant content or ads (which isn’t always a bad thing).
You can trust some cookies, but not all of them. First-party cookies are typically used to assist you. Third-party cookies are often more interested in tracking your behaviour than helping you out. If you don’t know who’s setting the cookie or why, it’s okay to be suspicious. When in doubt, say no or manage your preferences manually.