Server Name Indication (SNI) is an advanced version of TLS (Transport Layer Security) system networking protocol, which enables client to determine the host name which is being requested by the web browser at the very beginning of the handshake process. SNI helps the server to associate multiple numbers of SSL certificates, thus enabling a host of Secure - Hyper Text Transfer Protocol (HTTPS) websites, which can be accessed with the same IP address, eliminating the need for the same SSL certificate for all such websites.
In order to implement SNI practical, it is imperative for the end users to make use of web browsers that are compatible with it. Browsers that do not support SNI gets default certificate, and may come across several certificate warnings. These warnings can be only fixed by equipping the server with a wildcard certificate that is similar to the name of the website.