A cookie is a small piece of data that a web server sends to a user’s browser and that the browser can store. On later visits, the browser can send these cookies back to the relevant server. This structure allows websites to remember user sessions, store preferences, keep state information such as shopping carts and, in some cases, analyse user behaviour. MDN Web Docs explains cookies as small pieces of data that help web applications store limited amounts of information and remember state in the otherwise stateless HTTP protocol.
Cookies are often described as “text files stored on the computer,” but technically they are data records managed by the browser. The same cookies are not sent to the entire internet whenever a user visits a website; cookies work according to domain, path, duration, security and access settings. A cookie can only be used for the relevant domain or defined scope. For this reason, saying that cookies simply “track users” is not enough to understand how they work; the purpose, scope, duration and source of the cookie also matter.
One of the most common uses of cookies is session management. For example, when you log in to an e-commerce website, a session cookie may be placed in your browser. This cookie allows the website to understand that you are a logged-in user as you move between pages. The “remember me” option usually works through a secure session token or similar authentication structure rather than storing the username and password in plain text. For this reason, secure cookie management is critical for user account security.
Cookies can also be used to remember user preferences. Language selection, currency, theme preference, region selection, form preferences or products in the shopping cart can be preserved through cookies or similar storage technologies. This allows the user to avoid setting the same preferences again when they revisit the site. These types of cookies make the user experience easier and help the website function more effectively.
In marketing and advertising, cookies can be used to understand user behaviour and create more relevant advertising experiences. For example, if a user visits certain product pages, adds products to the cart or shows interest in a specific category, these signals may be used in remarketing or personalized advertising campaigns. However, this type of use is more sensitive in terms of user privacy and data protection rules. Therefore, for advertising, targeting and personalization cookies, clear information and valid consent processes should be properly structured when required.
Cookies can be classified in different ways. By duration, there are session cookies and persistent cookies. Session cookies are usually deleted when the browser is closed, while persistent cookies may remain on the device for a defined period. By source, there are first-party cookies and third-party cookies. First-party cookies are placed by the website the user visits, while third-party cookies may be placed by advertising, analytics, social media or other service providers. By purpose, cookies may be classified as strictly necessary, performance, functional, analytics, advertising and targeting cookies.
Strictly necessary cookies may be required for a website to perform its basic functions. Session security, shopping cart functionality, checkout steps or storing the user’s cookie preference may fall into this category. In contrast, analytics, advertising, remarketing or behavioural targeting cookies should be evaluated separately because they can process user behaviour in more detail. The Turkish Personal Data Protection Authority’s Cookie Practices Guide is an important source for website operators that process personal data through cookies, as it evaluates scenarios where explicit consent is or is not required.
If a website uses cookies, it is important to prepare a cookie policy or cookie notice. This text should clearly explain which cookies are used, for what purposes they are processed, how long they are stored, whether they are first-party or third-party cookies, the legal basis for processing and how users can manage their cookie preferences. It is not enough for the text to consist only of legal terminology. Users should be able to easily understand which data is processed and for what purpose.
Cookie management is not limited to publishing a policy text. The cookies used on the website should be technically inventoried, cookie categories should be identified correctly, consent mechanisms should be set up for non-essential cookies when required and users should be given the ability to change their preferences. If a user selects “reject,” advertising or analytics cookies should not continue running. Similarly, using misleading designs in cookie banners, pressuring users to accept or making preference management unnecessarily difficult can create trust and compliance issues.
When not misused, cookies can be beneficial for both users and website owners. For users, they provide advantages such as faster login, a more personalized experience, preserved shopping carts and remembered preferences. For website owners, they offer opportunities to improve user experience, understand technical performance, analyse the conversion funnel and manage marketing activities more efficiently. However, these benefits are not sustainable without transparency and user control.
Users can delete, block or manage cookies for specific sites through browser settings. Browsers such as Chrome, Firefox, Safari and Edge provide options to clear cookies and site data. However, deleting cookies may log users out of some websites, empty shopping carts or reset preferences. Therefore, users should also understand the effect that clearing cookies may have on their web experience.
From a security perspective, cookies should be configured correctly. For cookies related to sessions or authentication, security attributes such as Secure, HttpOnly and SameSite can be used. Secure helps ensure that the cookie is transmitted only over HTTPS. HttpOnly can reduce certain attack risks by limiting JavaScript access. SameSite helps control how the cookie is sent in cross-site requests. These settings are especially important for user accounts and payment processes.
In summary, cookies are small pieces of data that help websites remember user sessions, preferences, shopping cart information and certain behavioural signals. They can improve user experience, simplify e-commerce flows and support marketing measurement. However, cookie use should be managed carefully from technical, legal and ethical perspectives. A proper cookie policy, clear notice, valid consent mechanism, secure technical configuration and the ability for users to manage their preferences are the core elements of healthy cookie management.
