Computer Networks work based on Two type protocols.TCP and UDP. They are  collection of different communication protocols.Here give TCP/IP and its different protocols.

TCP ( Transmission Control Protocol)
   TCP is used for transmission of data from an application to the network.It is responsible for breaking data down into IP packets before they are sent, and for assembling the packets when they arrive.
IP ( Internet Protocol)
    IP takes care of the communication with other computers.It is responsible for the sending and receiving data packets over the Internet.
HTTP ( Hyper Text Transfer Protocol)     HTTP takes care of the communication between a web server and a web browser.It is used for sending requests from a web client  to a web server, returning web content  from the server back to the client.
SMTP ( Simple Mail Transfer Protocol)
    SMTP is used for transmission of e-mails.
MIME ( Multi-purpose Internet Mail Extensions )
     The MIME protocol lets SMTP transmit multimedia files including voice, audio, and binary data across TCP/IP networks.
IMAP ( Internet Message Access Protocol)
     IMAP is used for storing and retrieving e-mails.
POP (Post Office Protocol)
      POP is used for downloading e-mails from an e-mail server to a personal computer.
FTP (File Transfer Protocol)     FTP takes care of transmission of files between computers.
NTP ( Network Time Protocol)      NTP is used to synchronize the time (the clock) between computers.
DHCP ( Dynamic Host Configuration Protocol)      DHCP is used for allocation of dynamic IP addresses to computers in a network.
SNMP ( Simple Network Management Protocol)       SNMP is used for administration of computer networks.
LDAP ( Lightweight Directory Access Protocol)       LDAP is used for collecting information about users and e-mail addresses from the internet. 
ICMP - Internet Control Message Protocol
     ICMP takes care of error-handling in the network.Its is responsible to display error message when a link down.
 ARP ( Address Resolution Protocol)
       ARP is used by IP to find the hardware address of a computer network card based on the IP address. 
BOOTP ( Boot Protocol )
       BOOTP is used for booting  computers from the network.
PPTP (Point to Point Tunneling Protocol )
        PPTP is used for setting up a connection  between private networks