HTTPS stands for Hypertext Transfer Protocol Secure. It is the secure version of HTTP, the protocol over which data is sent between your browser and the website you are connected to. The 'S' at the end of HTTPS stands for 'Secure', meaning all communications between your browser and the website are encrypted. This is achieved through the use of SSL/TLS protocol, which also provides authentication, ensuring that you are connected to the intended website. HTTPS is essential for protecting sensitive transactions, like online banking or shopping, and is now a standard security practice for all websites.