A protocol means the rules that are applicable for a network or we can say that the common set of rules used for communication in network.
Different types of protocols are :
(i) HTTP : Hyper Text Transfer Protocol
(ii) FTP : File Transfer Protocol
(iii) SLIP : Serial Line Internet Protocol
(iv) PPP : Point to Point Protocol
(v) TCP/IP : Transmission Control Protocol/ Internet Protocol
(vi) NTP : Network Time Protocol
(vii) SMTP : Simple Mail Transfer Protocol
(viii) POP : Post Office Protocol
(ix) IMAP : Internet Mail Access Protocol
