Lesson
Introduction to Computer Networks and Network Devices
Learning objective
Describe how a computer works, define a computer network, and identify end and intermediary devices.
What is a computer?
A computer is an electronic device that follows instructions to process data. Data is information it can work with: numbers, words, pictures or sounds.
You do not need to understand everything inside a computer to start learning networking. First, let's see how one computer turns a simple request into a result.
How does a computer work?
Suppose you use a calculator app to add 2 + 2. Follow the three steps below:
- 1Input
You enter 2 + 2 using a keyboard or touchscreen.
- 2Processing
The CPU follows the calculator app's instructions to add the numbers.
- 3Output
The screen displays the result: 4.
RAM holds information in use. Storage keeps saved information after the power is off.
Storage is connected to processing, not a fourth step that must happen after every output.
The CPU (central processing unit) executes instructions. RAM is temporary working memory. Storage, such as an SSD, keeps applications and saved files. For example, you can save a document to open again later.
Hardware and software work together
Hardware
The parts you can touch: keyboard, screen, CPU, RAM and storage.
In our example: the keyboard receives your input, the CPU executes instructions, and the screen shows 4.
Software
The programs that tell the hardware what to do.
In our example: the calculator app provides the instructions for adding the numbers and displaying the answer.
Now connect the idea to networking: your computer can create and save a document by itself. But what if you want another device to receive it? That is where a network becomes useful.
What is a computer network?
Imagine you want to print a document from your laptop. The printer is across the room, with no cable directly connecting it to your laptop. How can your document reach it?
Both devices are connected to the same network. In this simple wired example, a switch connects them. Select each device below to meet its role.
Select a device to see its basic role.
A network lets connected devices exchange data and share resources. That connected group of devices is a computer network. The connections can be wired or wireless.
Why networks exist
Think of three things you already do with networks:
Send a message or share a file.
Several people can use one network printer.
Open a website or use an online learning platform.
LANs, WANs and the Internet
A local area network (LAN) connects devices in a limited place such as a home, office, or school. A wide area network (WAN) connects networks across larger distances. The Internet is a global system of interconnected networks.
Your local network and the Internet are not the same thing. Try disconnecting the Internet in this diagram. Which connections are still available?
Select a device to see its basic role.
This example uses an already configured local network printer, not a cloud printing service.
End and intermediary devices
An end device, also called a host, creates or receives information. Here, the laptop and printer are end devices.
An intermediary device connects devices or networks and helps information travel between them. Here, the switch is the intermediary.
Select a device to see its basic role.
This module introduces each role. Later modules explain the detailed decisions these devices make.
Identify device roles
Choose the hub, bridge, switch, or routed-network example. The animated packet stays within that valid arrangement, and a cloud pop-up introduces each active device. You can pause the tour or select a device directly.
Identify device roles
Choose one network example. Each view teaches one device arrangement without placing older and modern connectors in the same path.
See how a hub repeats one host's signal toward every other attached host.
Active: Laptop
Packet inspector
Inside the packet
Host or device decision
No frame is crossing a link during this step.
- Current stop
- Laptop
- Broad role
- Host