How do cookies work in web technologies?

Cookies are small text files stored on a user's device by a website to remember information about the user.

In web technologies, cookies play a crucial role in enhancing user experience and facilitating certain functionalities. When a user visits a website, the website sends a cookie to the user's device. This cookie, which is a small text file, is stored in the user's web browser. The cookie contains information that the website can use to remember the user and their preferences, such as login details, items in a shopping cart, or language settings.

Cookies are created when a new webpage is loaded. The website server sends a Set-Cookie header to the user's browser, which then stores the cookie on the user's device. The next time the user visits the same website, the browser sends the cookie back to the server in a Cookie header. This allows the website to 'remember' the user and their preferences, providing a more personalised browsing experience.

There are different types of cookies, each serving a different purpose. Session cookies are temporary cookies that are erased when the user closes their browser. They are used to manage the user's session, such as keeping them logged in as they navigate through the website. Persistent cookies, on the other hand, remain on the user's device even after the browser is closed. They are used to remember the user's preferences and actions over a longer period.

Cookies can also be categorised as first-party or third-party cookies. First-party cookies are created by the website the user is visiting, while third-party cookies are created by other websites that the user is not visiting. Third-party cookies are often used for online advertising and tracking user behaviour across multiple websites.

While cookies are essential for many web functionalities, they also raise privacy concerns. They can be used to track a user's browsing habits and personal information, which can be used for targeted advertising. Therefore, it's important for websites to obtain user consent before setting cookies, and for users to be aware of how their information is being used.