About Cookies

When browsing the web—whether on news portals, e-commerce platforms, or social media sites—we often encounter pop-up notices stating "This website uses cookies." For instance, when you log into your favorite social media app to check updates, or when you’re comparing prices of a new camera across multiple e-commerce sites, cookies are working behind the scenes to streamline these interactions. Yet many users lack a comprehensive understanding of what cookies truly are, how they function, and the potential implications for their online experience. In reality, cookies are a foundational component of modern web technology: they not only enhance browsing convenience by remembering personalized settings and user behaviors but also raise important privacy and security considerations. This article will break down the essentials of cookies—from their technical makeup to real-world applications—to help you fully grasp these "little assistants" that quietly shape your interactions with the digital world.

I. What Are Cookies?

Cookies are small text files generated and sent by website servers to users' browsers when a user first visits a site, which are then stored in designated directories on users' computers, mobile phones, or other internet-connected devices. Developed in 1994 by Netscape Communications to solve the problem of HTTP’s "stateless" nature—where the protocol itself doesn’t retain information about previous user interactions—cookies revolutionized how websites deliver personalized experiences. Each cookie typically contains key information such as the website's domain name, an expiration date, a unique randomly generated identifier (to distinguish individual users), and some basic user-related data—like preferences for page layout, language settings, font size preferences, dark mode settings, or even the last section of a news article you were reading. When the user revisits the same website, the browser automatically attaches these stored cookies to the HTTP request header sent to the server, enabling the website to quickly recognize the user's identity and retrieve previously saved information without requiring redundant data entry.
Cookies are generally tiny in size, ranging from a few bytes to around 4KB (a limit established by early web protocol standards to prevent excessive storage usage), so they occupy negligible storage space on devices—even hundreds of cookies together take up less space than a single low-resolution image. Crucially, cookies lack executable code and cannot carry viruses, malware, or malicious scripts—their sole purpose is to act as "messengers" that facilitate efficient information transmission between the client (user's browser) and the server. Most modern browsers, including Chrome, Firefox, and Safari, manage cookie storage through dedicated settings panels, allowing users to view, sort, or delete cookies associated with specific websites or all sites collectively. Additionally, since they are purely text-based, cookies cannot execute any actions on their own, making them fundamentally different from more complex web technologies like JavaScript or plugins that carry greater security risks.

II. Main Types of Cookies

Based on their intended purposes, lifecycle duration, scope of use, and the entity that sets them, cookies can be categorized into several common types, each serving distinct functions in the web ecosystem. Understanding these categories is key to managing your online privacy and optimizing your browsing experience:
  • Session Cookies: These cookies are temporary and only valid for the duration of the user's current browsing session—defined as the period from when the browser is opened until it is closed. They are created when the user first accesses a website and automatically deleted once the browser window (or all related tabs) is closed. Session cookies primarily store transient user operation data, such as active login status on a banking website (preventing the need to re-enter credentials for every transaction page or account summary view), items added to an e-commerce shopping cart, or progress in filling out long online forms (like job applications, loan applications, or survey responses). For example, when you add a laptop, headphones, and a laptop bag to your cart on platforms like Amazon or eBay, session cookies track these selections to ensure the cart contents remain consistent as you navigate between product pages, customer reviews, and the checkout process. Another common use case is online exam platforms, where session cookies ensure that students remain logged in during the entire exam duration and prevent unauthorized access to the exam interface if the browser is accidentally closed and reopened within the session window.
Persistent Cookies (Permanent Cookies): Unlike session cookies, persistent cookies have a predefined expiration date explicitly set by the website—this timeframe can range from a few days (for promotional cookies) to several years (for long-term user preferences). They remain stored on the user's device even after the browser is closed, persisting until their expiration date or until the user manually deletes them via browser settings. These cookies are designed for long-term personalization and convenience: they remember login credentials for social media sites (letting users stay logged in for weeks without reauthenticating), preferred language and currency settings on international websites (e.g., showing EUR and French on a European fashion site like Zara, or USD and English on its U.S. counterpart), or viewing history to deliver tailored content recommendations. A prime example is video streaming services like Netflix or Spotify, which use persistent cookies to recall a user's watchlist, playback progress (so you can resume a movie where you left off), and genre preferences (such as a love for sci-fi or classical music) across multiple browsing sessions. E-commerce platforms also rely heavily on persistent cookies to remember user-specific details like shipping addresses (with user consent), recently viewed products (displayed in a "Continue Shopping" section), or membership tier benefits, making the checkout process faster and more seamless for returning customers.
Third-party Cookies: These cookies are not set by the website the user is directly visiting (the "first-party" site) but by third-party entities such as advertising networks (e.g., Google Ads, Facebook Ads), analytics providers (e.g., Google Analytics), or social media widgets (e.g., Facebook "Like" buttons, Twitter "Share" buttons) embedded on the first-party site. Their primary function is to track user behavior across multiple unrelated websites to deliver targeted advertisements, measure ad campaign performance, or enable cross-site social features. For example, if you browse a travel blog that includes ads from a hotel booking platform like Booking.com, the booking platform may set a third-party cookie. Later, when you visit a recipe website, you might see ads for hotels in destinations you researched on the travel blog. Due to growing privacy concerns about cross-site tracking, many modern browsers now block third-party cookies by default: Safari’s Intelligent Tracking Prevention, Firefox’s Enhanced Tracking Protection, and Chrome’s Privacy Sandbox initiative all restrict or eliminate third-party cookie functionality to give users more control over their data.