The Internet Protocol Suite (commonly known as TCP/IP) is the set of communications protocols used for the Internet and other similar networks. The Internet Protocol Suite, like many protocol suites, may be viewed as a set of layers. Each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the upper layer protocols based on using services from some lower layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that can eventually be physically transmitted. The TCP/IP model consists of four layers. From lowest to highest, these are the Link Layer, the Internet Layer, the Transport Layer, and the Application Layer.

Some have attempted to map the Internet Protocol model onto the seven-layer OSI Model. The mapping results in the TCP/IP Link Layer corresponding to the OSI Data Link and Physical layers in terms of functionality. The Internet Layer is usually directly mapped to the OSI's Network Layer. At the top of the hierarchy, the Transport Layer is always mapped directly into the OSI Layer 4 of the same name. OSI's Application Layer, Presentation Layer, and Session Layer are collapsed into TCP/IP's Application Layer.

The following table provides some examples of the protocols grouped in their respective layers. See the below sections for details on each protocol.
Application     DNS, TFTP, TLS/SSL, FTP, HTTP, IMAP4, POP3, SIP, SMTP, SNMP, SSH, Telnet, RTP
Transport     TCP, UDP
Internet     IP (IPv4, IPv6), ICMP, IGMP
Link     ARP

    TCP/IP (Transmission Control Protocol/Internet Protocol) suite
    ARP (Address Resolution Protocol)
     DHCP (Dynamic Host Configuration Protocol)
     DNS (Domain Name System)
     FTP (File Transfer Protocol)
     HTTP (Hypertext Transfer Protocol)
     HTTPS (Hypertext Transfer Protocol Secure)
     ICMP (Internet Control Message Protocol)
     IGMP (Internet Group Management Protocol)
     IMAP4 (Internet Message Access Protocol version 4)
     NTP (Network Time Protocol)
     POP3 (Post Office Protocol version 3)
     RTP (Real-time Transport Protocol) - VoIP (Voice over Internet Protocol)
     SIP (Session Initiation Protocol) - VoIP (Voice over Internet Protocol)
     SMTP (Simple Mail Transfer Protocol)
     SNMP2/3 (Simple Network Management Protocol version 2 or 3)
     SSH (Secure Shell)
     TCP (Transmission Control Protocol)
     TFTP (Trivial File Transfer Protocol)
     TLS (Transport Layer Security)
     UDP (User Datagram Protocol)