1. What is a Computer Network?
A computer network is when two or more computers or devices (like mobiles and printers) are connected together so they can share information and resources (like files, internet, or printers). These devices talk to each other using wires or wireless signals like Wi-Fi.
This process of connecting is called networking.
For example:
In the picture, Computers A, B, and C are connected. They can share files and even send a print command to a shared printer.
2. Components of a Computer Network
There are two types of components:
A. Hardware Components (Physical parts):
Server – The main and powerful computer that manages the whole network and shares data with others.
Client – Other computers that receive or send requests to the server.
Node – Any device connected to the network (like computers, printers, or modems).
Transmission Media – The paths through which data travels, like cables or wireless signals.
Connecting Devices – Tools that help connect all the computers, like routers, switches, hubs, etc.
B. Software Components (Programs that help network run):
Network Operating System (NOS) – Special software that runs on the server and helps manage the network.
Protocols – Set of rules that devices follow to communicate. Common ones are:
TCP/IP – Basic internet communication
HTTP – Used for websites
FTP – For sending files
SMTP – For sending emails
3. Advantages of Computer Networking
Saves Money
Shares Data Quickly and Easily
Fast and Reliable Communication
Can Access Information from Anywhere
Shares Resources (like printers, internet)
Keeps Network Secure
4. Types of Computer Networks
Based on the size and area, networks are divided into four types:
a. Personal Area Network (PAN)
Small network around one person (like phone connected to laptop)
Uses Bluetooth, Wi-Fi, or USB
b. Local Area Network (LAN)
Network in a small area like a home, school, or office
Connects computers using cables or Wi-Fi
Used to share files, internet, and printers
c. Metropolitan Area Network (MAN)
Network in a city, used by governments or companies
Connects multiple LANs together
Uses fast cables like fibre optics
d. Wide Area Network (WAN)
Largest type of network – connects cities, countries, even the world!
The Internet is the biggest example
Can even connect to satellites in space!
Other Types of Networks
Intranet
It’s a private network for only company or organization people.
Example: School teachers can use it to share info, but students can’t access it.
Extranet
A private network that selected outsiders can use.
Example: A shop can let suppliers check order details using a password.
VPN (Virtual Private Network)
It gives a secure connection through the internet.
Keeps private info safe when working from home.
Networking Devices
Hub and Switch
Hub: Sends data to all devices.
Switch: Sends data only where it’s needed. (Smarter than a hub.)
Data Transmission Media (Ways to Send Data)
Wired Networking
Uses cables like twisted pair, coaxial, and fiber optic cables.
Fiber Optic Cables
Very fast, used in modern internet lines.
Wireless Networking
No wires. Uses radio waves to send data.
WLAN (Wireless Local Area Network)
Like home Wi-Fi. Lets laptops and mobiles connect without wires.
Network Protocols (Rules for Sending Data)
TCP/IP
Main rule set used on the internet.
Breaks data into packets and sends them to the right place.
HTTP
Used to open websites.
HTTPS is the secure version (safe for passwords, payments).
SMTP
Sends emails.
IMAP and POP3
Used to receive emails from the server.
Working in a Networked Environment
Computers in schools, offices, etc., are connected to share files, printers, and the internet.
Helps save time and resources.