Popular science: What are Cookies and Sessions?

1. What are cookies?

An analogy: Imagine you enter a coffee shop, you order a cup of coffee, and the waiter gives you an order receipt. This receipt contains the information about the coffee you ordered. You can find your coffee at any time in the coffee shop with the receipt.

Actually: In the online world, cookies are like this little ticket. When you visit a website, the server will send a small text file to your browser, which contains some information, such as your login status, shopping cart contents, etc. This text file is a cookie, and the browser saves it and sends it to the server the next time you visit the same website.

2. What is Session?

An analogy: Imagine you enter a gym and you apply for a membership card. There is no specific workout information on this membership card, but as long as you are present, the gym knows you are a member and can enjoy some privileges.

Actually: Session is like this membership card. When you log in on the website, the server will create a Session, assign you a special identification (such as an ID), and then store this identification in a cookie and send it to your browser. Every time you interact with the server, the server will identify you through this Session ID, know who you are and some of your status information.

3. What is the relationship between Cookie and Session?

Cookies are data stored in the user's browser, while Sessions are data stored on the server side.
Session usually uses the identifier in the cookie to track the user's status.

4. Why are Cookies and Sessions needed?

User status tracking: Allows the website to track the user's login status, shopping cart contents and other information to provide personalized services.
Security: Use Session to verify user identity and protect user privacy information.
User experience: Remember user preferences and provide more personalized and convenient services.

in conclusion:

Cookies are small text files stored in the user's browser to store some user information.
Session is a server-side status tracking mechanism, implemented through the identifier in Cookie.