SSL Certificate It is a server that complies with the SSL Secure Sockets Layer protocol digital certificate 。 The SSL security protocol was originally designed and developed by Netscape Communication of the United States. Its full name is Secure Sockets Layer. It specifies the mechanism to provide data security layering between application protocols (such as HTTP, Telnet, FTP) and TCP/IP. It is a security protocol implemented on the transmission communication protocol (TCP/IP), It adopts public key technology, which provides data encryption, server authentication, message integrity and optional client authentication for TCP/IP connections. Because this protocol solves the insecure problem of clear text transmission on the Internet very well, it was quickly supported by the industry and has become an international standard. The SSL certificate is issued by the "trusted root certificate authority" in the browser after verifying the server identity. It has dual functions of website authentication and encrypted transmission.