Internet Control Message Protocol(A required maintenance protocol in the TCP/IP suite that reports errors and allows simple connectivity. ICMP is used by the Ping tool to perform TCP/IP troubleshooting)
Internet Group Management Protocol(A protocol used by Internet Protocol version 4 (IPv4) hosts to report their multicast group memberships to any immediately neighboring multicast routers)
Internet Message Access Protocol 4(A standard client/server protocol for receiving e-mail. The user (or the user's e-mail client) can view just the heading and the sender of the letter and then decide whether to download the mail)