What are web cookies

A web cookie is a small text file stored in the client browser. It is sent to the browser by the server and stored on the user's computer or mobile device. Cookies are mainly used to track and identify users. and maintain session state across multiple requests.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Web Cookie (Cookie for short) is a small text file stored in the client's browser. It is sent to the browser by the server and stored on the user's computer or mobile device. Cookies are primarily used to track and identify users and maintain session state across multiple requests.

When a user visits a website, the server can send Cookie to the user's browser through the HTTP response header. The browser will store these cookies and automatically add them to the corresponding HTTP request headers in subsequent requests and send them back to the server. The server can identify the user based on the information in the cookie and store specific user preferences, login information, shopping cart contents and other data.

There are several points to note:

1. Security: The information stored in Cookies is clear text, so sensitive information (such as passwords) should not be stored in Cookies. For added security, cookies can be encrypted or use a secure connection such as HTTPS.

2. Limitations: There are limits on the number and size of cookies under each domain name. Usually there can be up to dozens of cookies under a domain name, and the size of each cookie is limited to a few KB to dozens of KB.

3. Privacy: Since cookies can be used to track user behavior and identify users, sometimes users may be concerned about privacy issues. For the purpose of user privacy protection, modern browsers provide cookie control options, and users can choose whether to accept or delete cookies.

In addition to session management, cookies have other uses, such as remembering login status, personalized recommendations, ad tracking, etc. Although cookies are widely used in web development, there are alternative technologies such as Web Storage, IndexedDB, and JSON Web Token (JWT).

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