1. ARPANET was the first wide-area packet switching network and helped establish the TCP/IP protocol, laying the foundation for the modern Internet. 2. A computer network connects computers together to share resources like access to the Internet, printers, and file servers. The Internet itself can be considered a large computer network. 3. The goals of computer networks are to share resources between connected computers, ensure high performance for multiple users, provide reliability through alternative data communication paths, increase scalability by adding more processors, and provide security to protect data from unauthorized access.

1. ARPANET:
The Advanced Research Projects Agency Network (ARPANET)wasthefirst wide-area packet-
switching network with distributed control and one of the first networks to implement
the TCP/IP protocol suite. Both technologies became thetechnical foundation of the Internet. The
ARPANET was established by the Advanced Research Projects Agency (ARPA) of the United States
Department of Defense.
What is Computer Network?
A computer network is a set of computers connected together for the purpose of sharing
resources. The most common resource shared today is connection to the Internet. Other shared
resources can include a printer or a file server. The Internet itself can be considered a computer
network.
Goals of Computer Network:
Sharing Resources: fromone Computer to another Computer over a network.
Performance: bymeasuring the speed of data transmission with number of users, connectivity and
the software used.
Reliability: makeseasyto use an alternativesource for data communication in case of hardware
failure or connectivity issues.
Scalability: increasesthesystem performance by adding more processors.
Security: isthemain characteristicsof Computer network where you can takenecessary steps for
protecting your data from unauthorized access.
Application of Computer Network:
• Business Applications: Abusiness application is a collection of components that provides a
business functionality that you can use internally, externally, or with other business applications.
• Communication Medium: It refersto the physical channel through which data is sent and
received. Data is sent in the form of voltagelevels which make up the digital signal.
• e-commerce: It isthebuying and selling of goods and services.
• HomeApplications: usedtoremotely control and manageconnected non-computing devices.
• Electronic commerce: It isa business model that lets firms and individuals buy and sell things
over the internet.
• Mobile Users:
Mobile Users:
1. HardwareEquipment: NIC,Server,Client, Peers, Transmission, Medium, Router, Bridge, Hub,
Switches, Gateway,Repeaters.
2. Software: NetworkOperating System, Protocols Switches.
3. Cables and Connectors: Twistedpair cable, Coaxialcable, Fiber-optic cable.
•Twisted pair cable: It isa type of wire in which two conductors of a single circuit aretwisted
together for the purposes of improving electromagneticcompatibility.
•Coaxial cable:It is commonly used by cable operators, telephone companies, and internet
providers around the world to convey data, video, and voice communications to customers.
•Fiber-optic cable: It is an assembly similar to an electrical cable, but containing one or
more optical fibers that areused to carry light. The optical fiber elements are typically individually
coated with plastic layers and contained in a protective tube suitable for the environment where
the cable is used.