What is the difference between PHP session and cookie?

Both Session and Cookie in PHP are used to store data between the server and the client.

The main differences are as follows:

1. Storage location: Cookies are stored in the client’s browser, while Sessions are stored on the server.
2. Security: Cookies are relatively insecure as they can be modified or deleted on the client side. On the other hand, Sessions are stored on the server and are not visible to the client, making them relatively more secure.
3. Storage capacity: Cookies typically have a limited storage capacity of around 4KB, while there is no specific storage capacity limit for Sessions but they do use server memory.
4. Cookie have a set expiration time, stored in the client’s browser, and can be retained until that time. On the other hand, Sessions typically end when the user closes the browser, but the expiration time can be extended.
5. Cross-domain issue: Cookies can be accessed across different domains and paths, while Sessions can only be accessed within the same domain and path by default.
6. Scenario: Cookies are primarily used to store small data, such as user login status and shopping cart information. On the other hand, sessions are more suitable for storing larger data, such as user information and session status.

In conclusion, Sessions are generally safer and have larger storage capacity than Cookies, but they do require more server resources. When deciding which method to use, it is important to consider specific needs and security factors.