The protocol that specifies how data is formatted and transmitted over the internet is the Hypertext Transfer Protocol (HTTP). It defines the rules for communication between web clients (browsers) and servers, allowing users to access websites and resources. Over time, HTTP has evolved, with HTTP/2 and HTTPS (secure version) providing enhancements such as better performance, security, and multiplexing. Understanding this protocol is crucial for web developers and anyone involved in building and maintaining web applications.