All these protocols use a client/server process.
Domain Name System (DNS) provides users with an automated service that matches or resolves resource names and email domains with the required numeric device network address. This service is available to any user connected to the Internet and running an application layer application such as a web browser or email client program.
Hypertext Transfer Protocol (HTTP) was originally developed to publish and retrieve Hypertext Markup Language (HTML) pages and is now used for distributed, collaborative, hypermedia information systems. HTTP is used by the World Wide Web (WWW) to transfer data from web servers to web clients.
Server Message Block (SMB) describes the structure of sharing network resources, such as directories, files, printers, and serial ports between computers.
Simple Mail Transport Protocol (SMTP) transfers outbound e-mails from the e-mail client to the e-mail server and transports e-mail between e-mail servers and so enables-mail to be exchanged over the Internet.
POP, or POP3 (Post Office Protocol version 3), delivers e-mail from the e-mail server to the client.