1. Introduction to Networks

2. When Personal Computers first appeared in business, software programs were designed for a single user. However as computers spread throughout business, and as developers began offering software designed for multiple users, many organizations quickly learned the importance of connecting computers; therefore, data communications became a major focus of the computer industry.

3. A network is a set of technologies (including hardware, software, and cabling or some other means) that can be used to connect computers together, enabling them to communicate, exchange information, and share resources in real time.

4. When data and programs are stored on a network and can be shared, individual users do not need to keep separate copies of the data and programs on their own computers.

5. Networking technology has become the most explosive area of growth in the entire computer industry. The demand for larger, faster, higher- capacity networks has increased as businesses have realized the value of networking their computer systems.

6. Four important benefits of using a network include: 1. They allow many users to access programs and data at the same time. 2. They allow users to share peripheral devices, such as printers and scanners. 3. They make personal communications easier. 4. They make it easy for users and administrators to back up important data files.

7. Network classifications: Networks classified by architecture:

8. Client/Server architecture – a client can send requests to, and receive services from, another typically more powerful computer called a server. The server can store programs, files, and data that are available to authorized users. The advantage is that application programs such as Microsoft Office, can be stored on the server and accessed by multiple users.

9. Peer–to–peer architecture – computers composing the network have equivalent capabilities and responsibilities, each acting as both client and server. Usually simpler to install and maintain and are less expensive.

10. Networks classified by coverage: Local Area Networks (LAN) - computers that are relatively near each other and are connected in a way that enables them to communicate by a cable, an infrared link, or a small wireless device. Can consist of just two or three PC’s connected together to share resources or it can include hundreds of computers of different kinds. Any network that exists within a single building, or even a group of adjacent buildings, is considered a LAN.

11. Wide Area Networks (WAN) – two or more LAN’s connected together, generally across a wide geographical area. For example, a company may have its corporate headquarters and manufacturing plant in one city and its marketing office in another. Each site needs resources, data and programs locally, but it also needs to share data with the other site. The company can attach routers connected over public utilities (telephone lines) to create a WAN. A WAN does not have to include any LAN systems. For example, two distant mainframe computers can communicate through a WAN, even though neither is part of a local area network.

12. Networks classified by users: Intranets – a network that is housed within an organization to serve internal users. Stored information is available only to authorized users, and certain kinds of information may be available only to specific persons, groups, or departments within the organization. All inquiries and messages entering or leaving the intranet pass through a firewall that prevents or restricts access to and from the network.

13. Extranets – an extension of an intranet that allows specified external users, including customers and business partners, access to internal applications and data via the Internet. It allows external users with a valid user ID and password to pass through the firewall and access certain resources in the organization’s network. For example, an automobile manufacturer can post a request for bids for raw materials, such as engine parts, seat covers, and tires.

14. Future Networks: New developments in fiber-optic technology, including the use of lasers to send optical signals through the air, could make high- speed data transmission available to more users. Researchers are also working to develop faster infrared transmission technologies over networks. The wireless industry will continue to see improvements both in the amount of data that can be transmitted and in transmission speed.