There is no single protocol used between a server and a client; the protocol depends on what the server and client are doing and how they are currently communicating.
POP (Post Office Protocol) - The protocol that an e-mail server and client usewhen the client requests the downloading of e-mailmessages.
Remote Desktop Protocol
The File Transfer Protocol is a standard network protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client-server model architecture using separate control and data connections between the client and the server
POP (post office protocol) is usually used to retreive emails from a server.
File Transfer Protocol
A File Transfer Protocol works on a client-server architecture and uses separate control and data connections between the server and the client. FTPs are used in businesses and government agencies world-wide.
HTTP (web traffic) may be used in either peer to peer networks or client server networks. Either way, it is the same protocol. It is used to transmit a browser request to a web server or to transfer a page from a web server to a client browser.
SMTP is push protocol, stateful protocol which is used for sending Mails from Client to Client or Server to Server. Generally SMTP uses the encryption method of 7bit or 8bit ISCII but HTTP dose not use that. HTTP is pull protocol which is preferred for sites demand and this is stateless protocol.
ordering a big mac, and getting it
We use mircsoft ourlook client to download email from email-server. It uses POP3 or IMAP protocol to download emails to client
File Transfer Protocol (FTP) is used for transferring files between an FTP client and an FTP server.
Typically User Datagram Protocol (UDP) is used for both the request from the client and the response from the server. However, sometimes when the response from the server is larger, it may be handled with Transmission Control Protocol (TCP).