Inside Look at the Internet
1.1.2 A Service Description
Chapter 1
1.1 What Is the Internet?
1.1.1 Nuts-and-Bolts Description
1.1.2 A Service Description
1.1.3 What Is a Protocol?
1.2 The Network Edge
1.2.1 End Systems, Clients, and Servers
1.2.2 Connectionless and Connection-Oriented Service
1.3 Network Core
1.3.1 Circuit Switching and Packet Switching
1.3.2 Packed-Switched Networks: Datagram Networks and Virtual-Circuit Networks
1.4 Access Networks and Physical Media
1.4.1 Access Networks
1.4.2 Physical Media
1.5 ISPs and Internet Backbones
1.6 Delay and Loss in Packets-Switched Networks
1.6.1 Types of Delay
1.6.2 Queuing Delay and Packet Loss
1.6.3 Delay and Routes in the Internet
1.7 Protocol Layers and Their Service Models
1.7.1 Layered Architecture
1.7.2 Layers, Messages, Segments, Datagrams, and Frames

The Internet allows distrubuted applications running on its end systems to exchange data with each other.

The Internet provides two services to its distributed applications;a connection-oriented reliable service and a connectionless unreliable service. The connection-oriented reilable service guarantees that data transmitted from a sender to a receiver will eventually be delivered to the receiver in order and in its entirety. The connectionless unreliable service does not make any guarantees about eventual delivery.