LocalStroage: cannot be accessed across domains. The maximum value is 5M. If the data exceeds the threshold, it will be lost and will not be carried when sending a request. SessionStronage: Data is cleared when the browser closes. Cookie: maximum 4K, insecure, is planted by the server, each request will carry cookies, waste traffic, mainly to solve the problem of HTTP stateless. Session: Cookie – based, relatively secure, content stored on the server