All About Cookies | Online Privacy and Digital Security

Cookies play a central role in the Internet ecosystem today. These small text files offer conveniences but also raise significant privacy concerns. This comprehensive guide will examine what cookies are on a technical level, how they are used to track you across the web, and what tools you have to control them. Arm yourself with knowledge to thoughtfully balance usability and privacy as you navigate the modern digital world.

What Exactly Are Cookies From a Technical Perspective?

Before we dive into what cookies do, let‘s look under the hood at what they actually are on a technical level.

Cookies are small text files, usually ranging from a few hundred bytes to a few kilobytes in size. They are stored in your web browser directory on your computer or mobile device. Chrome cookies are stored in a different location than Firefox cookies, for example.

A cookie contains information like a name, value, expiration date, domain name, path, and security settings. The domain sets the scope of the cookie and the path tells what directory it applies to. Many also contain unique identifiers to track individual users.

Cookies are transferred via HTTP headers when a web browser connects to a server. The server sends a Set-Cookie header that tells the browser to store the cookie. The browser then sends the cookie back via the Cookie header when making further requests to that domain. Cookies can be encrypted for security purposes.

Session cookies only last for the browsing session and are deleted when the browser closes. Persistent cookies have an associated expiration date and may last for years depending on the use case. Flash cookies follow a different storage model but work similarly.

So in summary, cookies provide a simple way for servers to store small amounts of data on your device through your browser to remember stateful information across pages. But they can also be abused for invasive tracking by embedding unique IDs.

The Different Flavors of Cookies You May Encounter

Beyond the technical aspects, it helps to understand the different categories of cookies you‘re likely to encounter while browsing:

• Strictly Necessary – These basic cookies enable core site functionality like keeping items in your shopping cart or remembering you‘re logged in. Disabling them breaks sites.

• Performance – These cookies collect info on site usage like traffic volumes to improve performance. They are anonymous.

• Functionality – These enhance services like remembering your preferences or language selection to personalize your experience.

• Targeting/Advertising – These track your browsing habits across sites to customize and target ads based on your inferred interests.

According to recent research 95% of all websites leverage cookies in some form, with over 70 tracking cookies on the average site. Under privacy regulations like GDPR, only strictly necessary cookies can be used without opt-in consent.

But between functionality and performance reasons, the average user often ends up agreeing to most cookie uses even if reluctant to share too much personal data. It‘s a complex balancing act between privacy and convenience.

The Omnipresent Surveillance of Third-Party Tracking Cookies

Many of the thorniest privacy debates around cookies center on third-party cookies placed by companies like Google, Facebook, and data brokers on sites you visit.

These largely fall under the targeting/advertising category and are primarily used to monitor your behavior across the web to infer interests and serve customized ads. For example, if you visit sites about running, you may see more Nike promotions on other sites.

A massive $227 billion industry has emerged around this kind of web tracking and ad targeting. Your online activity essentially becomes a commodity, bought and sold behind the scenes. Companies can build amazingly detailed profiles of individuals out of all their disparate browsing history.

Some especially concerning uses include building models about sensitive topics like health conditions or political views. There are also discriminatory practices like racially-biased ads. All of this happens without meaningful informed consent. This had led to calls for far more stringent regulations around cookie tracking.

Cookie Vulnerabilities Open Security Risks Too

Beyond just privacy violations, security experts warn that cookie tracking represents a significant emerging threat vector. If a hacker can steal a user‘s cookies, they can impersonate that user‘s account and login status.

This is usually done through cross-site scripting (XSS) attacks that inject malicious code allowing the attacker to hijack authentication cookies. There are also concerns around cookie vulnerabilities leading to wider malware infections.

Researchers found over 6 million sites had XSS vulnerabilities due to poor coding practices. This includes major players like Netflix and PayPal. Strategies like HTTP Only cookies aim to mitigate this by separating authentication cookies from browser JavaScript access.

But the general opaque nature of third-party cookie networks creates all kinds of risk. You are essentially trusting your privacy and security to the practices of companies you don‘t even directly interact with. Not an ideal scenario for peace of mind.

How You Can Regain Some Control Over Cookies

If this all sounds worrisome, you do have some control around cookie tracking depending on your priorities:

Browser Settings – All major browsers like Chrome, Firefox, and Safari let you clear cookies stored on your device. You can also set them to automatically clear each session. Opting out of third-party cookies limits cross-site tracking.

Private Browsing – Using your browser‘s private or incognito modes prevents it from retaining cookies between sessions. It‘s a quick way to disable tracking. However, cookies may still be active during that private session.

Browser Extensions – Tools like Ghostery, Privacy Badger, and AdBlock Plus detect and block tracking cookies so they are never downloaded. But they need to be updated as workarounds emerge.

Cookie Consent Tools – Browser extensions like Cookiebot make it easier to analyze and consent to cookies on a site-by-site basis to meet privacy regulations. Think before blindly clicking "Accept All".

VPN Protection – Using a virtual private network routes your web traffic through an encrypted tunnel. This hides your IP address and blocks sites from setting targeted cookies based on your location or device fingerprints.

Opt-Out Settings – Many sites and ad platforms have opt-out options to disable personalized ads and analytic cookies. But the process is often frustratingly opaque.

Take some time to understand the cookie management options in your own browsers. You can find guides for Chrome, Firefox, and Safari. I‘d also highly recommend some browser extensions like Privacy Badger and Cookiebot to reveal exactly how many hidden trackers are following you.

With a bit of diligence, you can find a good balance between privacy and convenience based on your personal needs. But it does require actively evaluating your options rather than accepting defaults.

Cookie Management Capabilities by Browser

Browser	Block 3rd Party	Clear on Exit	Opt-out Tracking	Mask IP Address
Chrome	Yes	Incognito	Limited	Extensions
Firefox	Yes	Private	Strong	Extensions
Safari	Yes	Private	Strong	Extensions
Brave	Yes	Yes	Strong	Built-in
Tor Browser	Yes	Yes	Strong	Built-in

Cookies Are Just the Tip of the Online Privacy Iceberg

While this guide has focused specifically on browser cookies, they represent just one facet of a far broader conversation around online privacy in the modern era. Your mobile apps have their own tracking identifiers akin to cookies. Device fingerprinting tracks you in the absence of cookies. Data brokers correlate online and offline data.

As more of our personal and professional lives move into the digital realm, we must grapple with emerging technologies of surveillance, data collection, and algorithmic influence. Navigating this world requires insight not just into specific technical mechanisms like cookies but the underlying desires to influence and the business models driving mass data harvesting.

The privacy risks surrounding something as small and ubiquitous as the cookie provide a window into those bigger questions around ethics, autonomy, and consent in an increasingly digitized society. So while adjusting your particular browser‘s cookie settings represents a good defensive start, the journey must continue toward more meaningful awareness, education, and advocacy around these issues.

Sources and Additional Information

• All About Cookies – Cookie information and browser management guides
• Cookies and Browser Privacy – Overview from the EFF
• Cybercookie Monsters – Workbook on investigating cookies
• The Cookie Economy – The New York Times deep dive