What is a Computer Network?

Table of Contents


A computer network is a collection of computers, servers, workstations, and peripherals that are interconnected through communication systems. These systems can include wired technologies such as Ethernet cables, fiber optic cables, and coaxial cables, or wireless technologies such as Wi-Fi, cellular networks, and satellite links.
Computer networks enable devices to communicate with each other, share data and resources, and collaborate on tasks. This communication can occur between devices that are located in close proximity, or over vast geographical distances.
The size of a computer network can vary widely, from a small local area network (LAN) that connects devices within a single room or building, to a wide area network (WAN) that spans multiple cities, countries, or even continents. LANs typically use Ethernet cables or Wi-Fi to connect devices, while WANs rely on long-distance communication technologies such as satellite links, microwave transmissions, and high-speed fiber optic connections.
In addition to their size, computer networks can also be classified based on their topology, or how devices are connected to each other. The most common topologies include star, ring, bus, and mesh networks.
Star networks are the most common, and are characterized by a central hub that connects all devices. In a ring network, devices are connected in a circular formation, with each device connected to the two devices adjacent to it. Bus networks use a single cable that connects all devices, while mesh networks use multiple connections between devices to create a redundant network.
Overall, computer networks are a fundamental component of modern computing and are essential for enabling communication, collaboration, and data sharing between devices and users.

There are several types of computer networks, including:

Local Area Network (LAN)

A Local Area Network (LAN) is a type of computer network that connects devices within a small geographic area, such as a home, office, or building. In a LAN, devices such as computers, printers, and servers are connected to each other using Ethernet cables, Wi-Fi, or other communication technologies.
The purpose of a LAN is to enable communication and resource sharing between devices within the network. For example, a LAN can allow multiple computers to share a single printer or access files stored on a shared server. This can increase efficiency and productivity by reducing the need for each device to have its own dedicated resources.
One of the key advantages of LANs is their speed and reliability. Because devices in a LAN are connected directly to each other, data can be transferred quickly and without the delays that can occur on larger networks. Additionally, LANs can be configured with redundant connections and backup systems to ensure that they remain operational even in the event of a failure.
LANs can be found in a wide range of settings, including homes, schools, businesses, and government agencies. They are often used as a building block for larger networks, such as Wide Area Networks (WANs) that connect devices across larger geographic areas.

Local Area Network Example.

Fig. 1 - Local Area Network Example

Metropolitan Area Network (MAN)

A Metropolitan Area Network (MAN) is a type of computer network that spans a geographic area larger than a Local Area Network (LAN) but smaller than a Wide Area Network (WAN). A MAN typically covers a single city or metropolitan area and is designed to provide high-speed connectivity to a large number of devices and users. MANs are often used by businesses, organizations, and government agencies to connect their offices and facilities within a city or region. They can also be used to provide internet connectivity and other services to residential customers in urban areas. The technology used in a MAN can vary depending on the specific requirements of the network. In some cases, a MAN may use fiber optic cables to provide high-speed data transmission, while in other cases it may rely on wireless technologies such as Wi-Fi or cellular networks. One of the key advantages of a MAN is that it can provide high-speed connectivity over a larger geographic area than a LAN, while still offering low latency and high bandwidth. This makes it ideal for applications that require large amounts of data to be transferred quickly, such as video streaming, online gaming, or cloud computing. Overall, a MAN is a valuable tool for connecting devices and users within a specific geographic area, and can play an important role in enabling communication, collaboration, and data sharing between individuals and organizations.

Wide Area Network (WAN)

A Wide Area Network (WAN) is a type of computer network that spans a large geographic area, typically covering multiple cities, states, or even countries. WANs are used to connect devices and users across great distances, and are essential for enabling global communication and collaboration.
WANs are typically made up of multiple interconnected networks, such as Local Area Networks (LANs) and Metropolitan Area Networks (MANs), that are connected to each other through routers, switches, and other networking equipment. These networks may use a variety of communication technologies, such as fiber optic cables, satellite links, microwave transmissions, or cellular networks, to transmit data over long distances.
One of the key advantages of a WAN is that it enables users and devices to communicate and share resources over vast distances. For example, a company with offices in multiple cities or countries can use a WAN to connect their offices and share data, applications, and resources such as printers and servers.
WANs can also be used to provide internet connectivity to remote locations, such as rural communities or offshore drilling platforms. This is typically done using satellite links or other wireless technologies that can provide connectivity in areas where traditional wired connections are not feasible.
Overall, WANs are an essential component of modern communication and are used by individuals, businesses, and organizations around the world to connect and collaborate across great distances.


The Internet is the largest and most widely used network in the world, connecting millions of computers and servers from all corners of the globe. Because of the vast distances between these devices, communication between them is facilitated through a variety of technologies, such as satellites, undersea cables, and optical fibers.
At its core, the Internet is a global network of interconnected computer networks that enables users to access and share information, services, and applications from anywhere in the world. Using standardized protocols and technologies, such as TCP/IP, DNS, and HTTP, data and information can be transmitted between devices and networks quickly and efficiently.
One of the key strengths of the Internet is its universal accessibility, available to anyone with an internet connection and a device capable of accessing the network. This has made it an incredibly powerful tool for communication, collaboration, and innovation on a global scale, with services ranging from email and social media to e-commerce and online gaming.
However, the Internet is not without its challenges and risks. Security threats, privacy concerns, and the spread of misinformation and harmful content are all potential hazards that users must be mindful of. Taking appropriate precautions, such as using strong passwords, updating software, and being cautious about sharing personal information, is essential to ensure a safe and secure online experience.


An intranet is a private computer network that functions like the Internet but is designed to serve the needs of an organization, such as a business, government agency, or educational institution. It is a closed network that is accessible only to authorized users within the organization and is typically used for internal communications, sharing of information, and collaboration.
In contrast to the Internet, which is a public network accessible to anyone, an intranet is a closed system that is secured behind a firewall and requires users to authenticate themselves before accessing the network. This enables organizations to control who can access information and resources on the network, ensuring that sensitive information is kept confidential and secure.
Intranets typically include features such as email, file sharing, document management, and collaboration tools, all of which are designed to facilitate communication and collaboration within the organization. They may also include customized applications and tools that are specific to the needs of the organization, such as HR or financial management systems.
Overall, an intranet can be a valuable tool for improving communication, collaboration, and productivity within an organization. By providing a secure and private network that is tailored to the needs of the organization, an intranet can help to streamline workflows, improve decision-making, and facilitate the sharing of knowledge and resources among employees.


An extranet is a private network that connects two or more organizations, allowing them to share information, collaborate on projects, and conduct business transactions securely over the Internet. It is an extension of an organization's intranet, allowing authorized users outside of the organization, such as customers, partners, or suppliers, to access specific resources and services on the network.
Like an intranet, an extranet is a closed network that is secured behind a firewall and requires users to authenticate themselves before accessing the network. However, unlike an intranet, which is designed for internal use only, an extranet is designed to facilitate communication and collaboration between organizations, providing a secure platform for sharing information, coordinating projects, and conducting transactions.
Typically, an extranet will provide users with access to specific resources and services, such as customer support, supply chain management, or project management tools. This can help to streamline workflows, improve collaboration and coordination, and enhance the overall efficiency of business operations.
Overall, an extranet can be a valuable tool for improving communication and collaboration between organizations, helping to build stronger relationships and more effective partnerships. By providing a secure and private platform for sharing information and conducting transactions, it can help to facilitate business processes and create value for all parties involved.

Networking Devices

Rate of Data Transfer

In cable networks, data is transferred one bit a a time; this is called serial data transfer. Data is tranfered over netwrok cables at a certain rate (speed) given as bits per second; for example: 100 bps (or bit/sec) means that 100 bits ( 1's and 0's) are transfered in one second.

IP address

An IP address, or Internet Protocol address, is a unique numerical label assigned to every device connected to a computer network that uses the Internet Protocol for communication. This address serves two main functions: identification of the device on the network and addressing of data packets that are sent over the network.
An IP address is typically represented as a series of four numbers separated by dots, such as "". There are two main types of IP addresses: IPv4 and IPv6. IPv4 addresses are 32-bit numbers and are the most common type of IP address in use today, while IPv6 addresses are 128-bit numbers and are gradually being adopted to replace IPv4 due to the increasing number of devices connected to the internet.
IP addresses can be assigned in a variety of ways, including through manual configuration by a network administrator, automatic assignment through a DHCP (Dynamic Host Configuration Protocol) server, or static assignment. An IP address can be used to track the geographic location of a device, although this information may not be completely accurate or reliable.

Links and References

1 - Computer Networking: A Top-Down Approach (6th Edition) 6th Edition - James F. Kurose and Keith W. Ross - ISBN-10: 0132856204
2 - Computer Networks (5th Edition) 5th Edition - Andrew S. Tanenbaum and David J. Wetherall - ISBN-10: 0132126958