What is a cookie:
Refers to the data stored on the user's local terminal by some websites for session tracking in order to identify the user.
Cookies can only store a small amount of data.
Taking Baidu's official website as an example, cookies include request cookies and response cookies in request and response headers respectively.
How are they different?
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The request header cookie, the http request message informs the server of the domain in the current page and the cookie information in effect through the cookie field.
The set-cookie in the response header, the http response message informs the client that the following cookie information needs to be saved through set-cookie.
