Why do I keep seeing those cookie consent banners popping up with disclosures? Well cookies are a fundamental part of how the modern web functions. Nearly every website you visit uses them in some form, from e-commerce platforms to news sites and social media (see what the Meta-Pixel Does). But why are they so ubiquitous? For those acting as a webmaster for your company and want help with privacy compliance and to educate yourself about what web cookies are, how they work, the different types, and the key reasons companies rely on them. We’ll also cover the benefits for both businesses and users, privacy implications, regulatory requirements, and the evolving landscape with new privacy laws coming out every year.
What Are Web Cookies?
Web cookies (also known as HTTP cookies or browser cookies) are small text files that a website’s server sends to your browser. The browser stores them on your device and sends them back to the server on subsequent visits. This allows websites to “remember” information about you across page loads or sessions.
Cookies were invented in 1994 by Lou Montulli at Netscape to solve the problem of stateless HTTP protocol — the web originally had no way to maintain information between requests. Without cookies, every interaction would be independent, like starting a new conversation each time you load a page.
For a technical deep dive, see the MDN guide on Using HTTP cookies.
Cookies typically contain key-value pairs, such as a session ID, user preferences, or tracking identifiers. They are limited in size (usually ~4KB per cookie) and can have attributes like expiration dates, security flags (e.g., Secure, HttpOnly), and domain restrictions.
How Do Cookies Work?
When you visit a website:
- Your browser sends an HTTP request to the server.
- The server responds with content and optionally a
Set-Cookieheader containing cookie data. - The browser stores the cookie.
- On future requests to the same domain (or related domains for third-party cookies), the browser automatically includes the cookie in a
Cookieheader.
This process enables stateful interactions on a stateless protocol. For example:
- Adding items to a shopping cart persists across pages.
- Staying logged in after closing and reopening the browser.
Detailed explanation: MDN Set-Cookie header.
Types of Cookies
Cookies are classified in several ways:
By Duration
- Session Cookies: Temporary; deleted when you close the browser. Used for short-term tasks like maintaining a login during a single session.
- Persistent Cookies: Remain on your device until they expire or are deleted. Used for long-term remembrance, like saved preferences.
By Source
- First-Party Cookies: Set by the website you’re directly visiting. Generally used for core functionality and personalization.
- Third-Party Cookies: Set by domains other than the one you’re visiting (e.g., ad networks embedded on the site). Primarily used for cross-site tracking and advertising.
By Purpose (Common Regulatory Categories)
- Strictly Necessary/Essential Cookies: Required for the site to function (e.g., shopping carts, logins). No consent needed under most laws.
- Performance/Analytics Cookies: Track site usage (e.g., via Google Analytics) to improve performance.
- Functionality/Preference Cookies: Remember choices like language or theme.
- Targeting/Advertising Cookies: Enable personalized ads across sites.
Why Do Companies Use Cookies? The Main Reasons
Companies use cookies for a mix of essential, operational, and commercial purposes. Here’s a breakdown:
1. Essential Functionality and Session Management
The web is stateless by design — without cookies, sites couldn’t maintain context. Cookies enable:
- Keeping users logged in (authentication cookies).
- Managing shopping carts in e-commerce.
- Preventing form resubmissions.
Without these, you’d have to re-login on every page or lose cart items. This is why even minimal sites use session cookies.
Example: Wikipedia notes authentication cookies as a core use.
2. Personalization and User Experience Enhancement
Cookies remember preferences:
- Language or region settings.
- Display modes (dark/light theme).
- Recommended content based on past views.
This creates a tailored experience, increasing user satisfaction and time on site. For businesses, it boosts engagement and retention.
Kaspersky explains how cookies streamline experiences like remembering logins and carts (What Are Internet Cookies? – Kaspersky).
3. Analytics and Performance Optimization
Performance cookies collect anonymous data on how users interact with a site:
- Page views, bounce rates, navigation paths.
- Device types and error reports.
Tools like Google Analytics rely on these to help companies identify issues (e.g., slow pages) and improve UX. This data drives A/B testing and feature decisions.
Benefit: Sites become faster and more user-friendly over time (Cloudflare: What are cookies?).
4. Advertising and Marketing
This is the most controversial — but lucrative — use:
- Third-party cookies track users across sites to build profiles.
- Enable retargeting (e.g., seeing ads for products you viewed elsewhere).
- Measure ad effectiveness and optimize campaigns.
Ad-supported sites (news, social media) depend on this for revenue. Social media platforms use cookies for personalized feeds and ads.
Benefits for Users
While privacy concerns dominate discussions, cookies provide real advantages:
- Convenience: Auto-login, saved carts, personalized recommendations.
- Better content: Sites adapt to your needs (e.g., local news, preferred products).
- Free services: Ad-supported sites remain accessible without paywalls.
Benefits for Businesses
- Increased conversions: Personalized experiences lead to higher sales.
- Data-driven decisions: Analytics improve products and reduce churn.
- Revenue generation: Targeted ads yield better ROI for advertisers.
- Competitive edge: Sites without personalization lose users to those that offer it.
Privacy Concerns and Legal Regulations
Cookies can collect sensitive data, enabling tracking without clear user awareness. Third-party cookies are particularly invasive for cross-site profiling.
Key regulations:
- GDPR (EU): Requires informed, granular consent for non-essential cookies. Strictly necessary ones are exempt.
- ePrivacy Directive: Complements GDPR for cookies.
- Similar laws: CCPA (California), LGPD (Brazil).
The Future of Cookies: Third-Party Deprecation and Alternatives
Google originally planned to phase out third-party cookies in Chrome by 2024–2025 but abandoned full deprecation in 2024 due to industry and regulatory feedback. Now they have said that third-party cookies remain supported, but with enhanced user controls and privacy-focused alternatives gaining traction and then there’s the idea of fingerprinting which is another way to determine a website visitor that we’ve covered. .
Key developments:
- Google’s Privacy Sandbox (e.g., Topics API) for interest-based advertising without individual tracking.
- Alternatives include first- and zero-party data, contextual targeting, universal IDs, and data clean rooms.
Why Have Cookies on a Website?
Companies use cookies because they solve core web limitations: enabling state, personalization, analytics, and monetization. While essential for modern experiences, their tracking potential has led to strict regulations and technological shifts.
Users benefit from convenience and tailored content, but should understand consent options. Businesses must balance utility with privacy compliance.
Why Have a Cookie Consent Banner?
This is a requirement if you’re going to be running cookies and tracking on your site and targeting visitors. If you don’t have a banner there’s no functional way to let users make a consent choice outside of running a tool like the Captain Compliance consent banner. If you need assistant and want to do a free privacy audit the team of privacy experts can evaluate your risk and help you make a risk decision on how to handle.
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