What is the difference between cookie and session? (detailed introduction)

This article brings you what is the difference between cookies and sessions? (detailed introduction) has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Session is another mechanism for recording client status. The difference is that Cookie is saved in the client browser, while Session is saved on the server. When the client browser accesses the server, the server records the client information on the server in some form. This is Session. When the client browser visits again, it only needs to find the customer's status from the Session.

If the Cookie mechanism determines the customer's identity by checking the "passport" on the customer, then the Session mechanism confirms the customer's identity by checking the "Customer Details" on the server. Session is equivalent to a customer file created by the program on the server. When a customer comes to visit, he only needs to query the customer file table.

Session principle in plain language: When you access the server once, the server will open up a space in the memory, return the only key to open the space, and then return the key to the browser. When you visit for the second time, the browser will carry this key to the server to open the corresponding space. If the space has been destroyed, it will open up a new space and return the new key to the browser.

DIFFERENCE	cookie	session
Definition	The website stores the user in order to identify the user’s identity Data on the local terminal (usually encrypted)	Data saved by the server to track user status
Different access methods	can only save ASCII characters and cannot directly access objects	can access any data type
## Different privacy policies	are stored on the client, visible to users, and can be modified and copied	Stored on the server, transparent to users and more secure
The validity period is different	You can set it to be valid for a long time, just set a particularly large expiration time	Shorter validity period
Browser Supporting different	requires client browser support. If the browser disables or does not support cookies, you need to use session and URL address rewriting (append the session id directly to the end of the URL path), which can be set to be valid in all windows or valid in the current window and sub-windows	Only valid within this browser window and sub-window
Cross-domain support for different	Support cross-domain name access	Does not support cross-domain name access, the session is only valid within the domain name where it is located

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