The domain name<span> part of an email address has to conform to strict guidelines: it must match the requirements for a </span>hostname<span>, consisting of letters, digits, hyphens and dots. </span>
A protocol is a set of rules that governs the communications between computers on a network.
1. HTTP or HTTPs. This stands for Hypertext Transfer Protocol or Hypertext Transfer Protocol (secure).
2. FTP (File Transfer Protocol)
3. Email Protocols (POP3, IMAP, SMTP)
4. TCP(Transmission Control Protocol) and UDP(User Datagram Protocol)
Hoped that helped