Lessons 1
Learn IT the simple, visual, beginner‑friendly way.
Introduction to Computers
Learn the basics of computers in a simple, visual, and easy‑to‑understand way. This lesson explains what a computer is, how it works, and the key parts every beginner should know.
Understanding Operating Systems
Understand what an operating system is, how it controls your computer, and why it’s essential for running apps, managing files, and interacting with your device. A simple, visual explanation for absolute beginners.
“Ready to Learn More?”
What You Will Learn
By the end of this lesson, you will understand:
• What a computer interface is
• The difference between UI, VUI, and NIC
• Why interfaces matter in everyday technology
• Real‑life examples you already use without noticing.
| Interface Type | Meaning | Example | Who Uses It |
|---|---|---|---|
| UI | Visual interface you click or tap | Windows, Android, Websites | Everyone |
| VUI | Voice-based interface | Siri, Alexa, Google Assistant | Hands-free users |
| NIC | Natural interaction (gestures, movement) | VR, Gaming sensors | Gamers, advanced systems |
Which interface uses voice commands?
A- UI
B- VUI
C- NIC
D- BIOS
What is a UI?
- A voice system
- A visual interface
- A network device
- A storage tool
Which interface uses gestures and movemen
A-NIC
B-UI
C-VUI
D-CLI
List 3 interfaces you used today and identify their type (UI, VUI, or NIC).
Example:
- Phone home screen → UI
- Google Assistant → VUI
- VR game → NIC
In the next lesson, we’ll explore how these interfaces work behind the scenes and how they shape your experience with technology. Subscribe and follow our Academy for more beginner‑friendly IT lessons.”
Next Lesson: Types of Computer Systems (Desktop, Laptop, Tablet, Server)
Lesson 3
Introduction of Network Lesson
A network is a group of computer systems that are interconnected so they can share information with each other. The computer you’re using to watch this video has a network connection to the computer the video file is stored on. Computer networking refers to the practice of connecting multiple computing devices together to share resources, exchange data, and communicate efficiently. These devices can include computers, servers, printers, and mobile devices.
Networking Components
These devices can be our computer, tablet, mobile phone, gaming console, IoT device, or server. We often refer to these as network nodes or hosts. Once we have our devices, we have to connect them all together. Devices on a network can be connected
using a variety of transmission media. We can use twisted-pair cabling, fiber optics, or even wireless radio signals. To use a specific transmission medium, a device needs the appropriate network interface. The interface’s job is to convert the digital data flowing in and out of our device into a signal that can be transmitted on the network medium. For example, if we’re using twisted-pair cabling, our network interface needs to have the appropriate connection for that cable. Each device on the network has to have a network interface to send and receive data. In the old days, networks were often small, and we could directly connect devices to each other. Today’s networks are much larger and work better by having a central connection point, such as a switch. For wireless networks, we can use an access point to connect everything together. We can also use a router to connect multiple networks together. The final piece of a network is the standards that’ll be used to define how the data is formatted. These standards are known as network protocols. If devices aren’t using the same protocols, they won’t be able to communicate or understand each other. You’ll see different protocols depending on the network and type of data that’s being transferred. Tying all these components together allows us to design our networks the way we want, no matter how large or small. Once we’ve got our devices physically connected, we need to configure the network addresses so that each device knows which network they’re connected to.
Network Addressing
If you think about it, a network is just like a neighborhood. Every device has to have a unique identifier, just like every house on a street does. This unique identifier for a building is its address, and every device on the network has its own address as well. For example, TestOut is located on a street named South Main Street, and our building number is 50. If we break down this address, 50 is the unique building number that distinguishes it from all other buildings on South Main Street. Now, another building on the next street over can also have the building number 50, but because it’s on a different street, it shouldn’t get confused with ours. We can apply this same addressing principle to networking. Each network address has two parts—the network , which is equivalent to the street name, and the host ID, which is the unique building number. A network address is written out using an IP address. We have two types of IP addresses—IP version 4 and IP version 6. For now, we’ll look at IP version 4. Here’s a typical IPv4 address. Each section of this address is called an octet because it consists of 8 bits—or 1s and 0s—and each octet is separated by a period. The first three octets here represent the network ID.
This means that every device on the network will start with 192.168.1. The last octet is the host ID and will be different for every network device. Depending on the network’s size, the first three octets won’t always represent the network ID. Sometimes, it’s just the first two or even just the First one, and remaining octets are the unique host ID. We can look at the subnet mask to know which octets are the network ID and which are the host ID. The subnet mask is important to the IP address because it gives context to which network or subnet it belongs to. Each octet in the subnet mask consists of a value that identifies the IP address’s network portion or host portion. If the whole subnet mask octet is identifying the network, a value of 255 will be indicated. If a subnet mask octet is 0, that always identifies the host portion.In this example, the subnet mask has a 255 value for the first two octets, and since there are zeros for the other octets, the two 255s identify 192.168 as the network ID. The host ID consists then of the last two octets.
In this case, that’s 0.50. When you look up a device’s IP address, the subnet mask will also be displayed so that you know which portions of the IP address are which.
This information helps you troubleshoot any communication issues you might be experiencing.Oftentimes, we have one large network, and it makes more sense to separate it into smaller ones. Each of these smaller networks is called a subnet, which is kind of like a street. That’s why we need the subnet mask. It’s what lets us know which network our devices are connected to and what the IP address should be on that subnet. For two devices to communicate, they need to have a unique IP address.
If they’re part of the same subnet—or same street, as it were—they’ll be able to easily communicate. If they’re on different subnets, the traffic will need to be sent through a router—known as a default gateway—which will then forward it on to its destination subnet. This is why it’s important to verify the network IDs and to make sure that your devices have the correct IP address and are on the correct subnet.
Networking Benefits
Setting up and configuring a network takes a lot of work and can be complicated, but the benefits make it worthwhile. One of the main benefits is the ability to share resources, like files and printers. Sharing resources allows you to be cost effective while still providing the necessary resources to your users. For example, everyone needs to print stuff off occasionally, but it’s more cost effective to have a single printer for multiple users instead of giving each user their own. Networks can also consolidate storage.
Instead of requiring employees to store data on their local workstations, they can save
data in a central location on a file server. They can even save data on a
network-attached storage device. Being able to share files over the network makes collaboration easier. It also makes it easier for the network administrators to back up and protect important data in case there’s a disaster. Implementing email, instant messaging, or even social media allows users working on a project to collaborate with each other no matter where they’re located. We can add workflow management to the mix to help track projects and organize them more efficiently. From the administrative side, a network makes management a whole lot easier. Instead of having to go to individual computers to back up data or troubleshoot, you can handle these tasks remotely. The network also provides a centralized management location for user accounts and security. There are many other benefits to networking that you’ll discover.
The ability to connect our devices together to share resources has transformed how organizations operate. To be a successful technician, you absolutely must be familiar with networking.
Summary
That’ll wrap up this lesson. In this lesson, we first looked at the different components that make up a network, including the transmission medium, the interface, and others.
Then we went over the basics of network addressing and how an IP version 4 address is formatted. Finally, we covered some of the benefits to networking, including sharing resources and having a central location for administration.
Lesson 4
Network Types
When we decide to set up a system, we first need to determine which type of network will work best for our needs. There’s a lot that goes into configuring a network, and we need to determine what we want the role of each device to be and how it’ll best fit in our environment. In this lesson, we’ll look at the different network classifications, their components, and how we can best use each one.
Network Roles
Before we dive into network types, we need to understand the two basic roles of
networking devices—the server and the client.
A server is any host that provides a network resource, and
the client is any host that consumes those network resources.
Peer-to-Peer Network
The first network type to go over is the peer-to-peer network. With this setup, each host can act as either a server or client. For example, if we’re sharing files over the network, the host sharing the file is acting as the server, and any host accessing the file is the client.
Peer-to-Peer Network Advantages
Peer-to-peer networks, or workgroups, have several different advantages.
They’re very easy to implement and are relatively inexpensive. You can create a peer-to-peer network using the existing hosts in your organization and configure
everything through the operating system.
There’s no special software you need to purchase.Once you’ve configured hosts on your peer-to-peer network, you can then share printers and storage devices with minimal configuration. All you have to do is share your locally connected resources.
Peer-to-Peer Network Disadvantages
The problem with this network type is that as it grows, the peer-to-peer model becomes incredibly difficult to manage. These networks have no centralized controls, which can lead to major issues. For example, if we have a host sharing a printer, but the user takes the day off from work and their computer is turned off, no other user will be able to access that printer.
We also have no central file storage. This means that if we need to perform backups, we have to go to each and every computer to back up data.
Another thing to keep in mind is that if we’re sharing files on a host, a user could easily delete or move files
on accident, causing others to lose all of their work.
As you can see, a peer-to-peer network is relatively
inexpensive and easy to implement, but in a large
enterprise environment, this just won’t work.
Client-Server Networks
For larger environments, you want to set up a client-server network model.
With this setup, we have clearly defined roles for our host machines. Specific machines act as servers and others act as clients. We configure the servers to handle access to network resources, such as files and printers.
The servers can also be configured to host websites and provide a centralized
management system for the administrators. User accounts, sharing permissions, and other network management tasks are all handled in this way.
In order to set up a client-server network, you need to have different operating systems installed on the various systems.
Client-Server Operating Systems
First, client workstations need to use a desktop operating system that allows the users to do their daily work, like running desktop applications.
They also have to have some type of client software installed so that they can connect
to the server and use shared resources. The server, on the other hand, needs to use a
specialized operating system that’s optimized to perform only server-oriented tasks.
We don’t use the server to perform word processing, create spreadsheets, or do anything like that. The server operating system is designed strictly to provide network resources and management.
Client-Server Network Disadvantages
The biggest drawback to a client-server network is the cost. Server hardware and operating systems are much more expensive than those used by client workstations.
Unlike in a peer-to-peer network where we just tend to throw things together, a client-server network requires much more planning. We need to plan which servers will perform which tasks, where the servers will be located, and how our clients will connect.
In general, most of the networks you’ll deal with will be client-server. Now, depending on the size and how it’s being utilized, a network can be categorized in a few different ways.
Client-Server Network Advantages
A client-server network provides quite a few benefits, namely that it’s easily scalable.
A client-server network can support as many hosts as we need, and it also provides us with a centralized management system that makes configuration and troubleshooting much easier. For example, if we’re having issues with users being unable to access a network share, we start by checking the file server’s storage. We don’t have to go around to different hosts to track down the issue. This central location makes it much easier to identify problems and fix them with less downtime.
Body Area Network (BAN)
One of the smallest network types
is the body area network, or BAN.
Wearable devices, like smart watches, fitness
trackers, and medical implants, make up a BAN.
Personal Area Network (PAN)
ext is the personal area network, or PAN.
This is a small network that connects
devices within a user’s immediate area.
The most common example of a PAN is when you
connect your Bluetooth earbuds to your cell phone.
Local Area Network (LAN)
After that, we have the local area network, or LAN.This is the basic network setup that
connects multiple hosts together within a
building using cables, switches, and routers.
If we connect devices on the LAN using wireless radio
signals, this is called a wireless LAN, or WLAN.
Campus Area Network (CAN)
The next category is the campus area network,
orCAN, also known as a corporate area network.
A CAN is established when multiple LANs are
connected together within a limited area, such as
a college campus or between different buildings
that all belong to the same organization.
Metropolitan Area Network (MAN)
Oftentimes, there will be several LANs that are
connected to each other within the same city.
In this situation, all of the networks
within the same metropolitan area constitute
a metropolitan area network, or MAN.
Wide Area Network (WAN)
We can continue expanding the networks
and connect them in different cities.
The connections between them are called wide area
network links, and this collection of connected
networks is called a wide area network, or WAN.
Storage Attached Network (SAN)
The last network category we’ll look at is the storage attached network, or SAN.
The SAN is a specialized network that provides high-speed access to storage.
Instead of having different servers handling file
storage, we have specialized hardware that makes it easy for our hosts to access any needed data.
A SAN is fault-tolerant, secure, and provides great data protection.
As you can see, there are many different ways to implement a network.
It’s important to understand network components so that
We know how to best plan for the network setup we want.
Summary
That’ll wrap up this lesson.
In this lesson, we first looked at the two main types
of the network, which are peer-to-peer and client-server.
We went over how these network types work and
the advantages and disadvantages of each one.
Then we covered the different network
categories based on size and use.
These include BANs, PANs, LANs,
WLANs, CANs, MANs, WANs, and SAN
Computer & Technology Basics Course for Absolute Beginners – freeCodeCamp.org
LESSON 5
ports and protocols
1. Ports and Protocols
Whenever we send data across the internet or over a network, a protocol is used specifically for that data and the way in which it’s being transmitted.
A protocol is just a set of rules that define how devices are supposed to communicate with each other. Each protocol uses a specific port to send and receive traffic through, and you can think of a port like a numbered door on the host device.
There are 65,536 possible ports, but most aren’t utilized very often. The port number tells the host device which type of traffic is being sent and where to send it to. Other network devices, such as firewalls, also use port numbers to block or reroute traffic.
In this lesson, we’re going to look at some of the most commonly used ports and protocols you’ll see in networking.
- FTP
The first ones we’ll look at are ports 20 and 21, which go with File Transfer Protocol, or FTP.
We make use of FTP when we need to transfer files between a server and a client.
FTP is actually one of the few protocols that uses two ports. Port 21 is used to transfer the control information, like which files to send and authenticate.Port 20 actually transfers the data.
3. SSH
Port 22 is utilized by Secure Shell, or SSH.
This protocol allows two devices to communicate with each other securely through encryption. While it can transfer files, we typically see SSH used to securely log into a remote network device or system.
4. Telnet
Telnet is another protocol that allows us to remotely
connect to another device on the same network. Telnet uses port 23.
The problem is that this protocol doesn’t utilize any encryption, so it’s really been replaced by SSH. But we need to be aware of it and how we may see it used.<br>
5. RDP
Another common remote protocol is Microsoft’s Remote Desktop Protocol, or RDP.
RDP is a proprietary Microsoft protocol that runs on port 3389 and allows us to log in remotely to another Windows-based device. RDP allows us to actually see the remote computer’s display and use our local input devices, such as the mouse and keyboard, to perform tasks from our own machine. This protocol is extremely helpful when you’re
troubleshooting device issues from across the network.
6. NetBIOS
On most networks, Network Basic Input/Output System, or NetBIOS is used to share files and communicate locally. As networks became more sophisticated, NetBIOS
was combined with TCP so that it could be routed. NetBIOS with TCP is known as NetBT, but we still refer to it as NetBIOS. It uses port 139 to establish a connection
between two computers and port 137 to transfer any information back and forth during the session. NetBIOS requires each computer to have a unique NetBIOS computer name so there’s no confusion.
This is especially important on a Microsoft network.
7. SMB
Server Message Block, or SMB, protocol is typically used to share and transfer data.
SMB uses TCP to transfer data through port 445, which makes it very reliable.
Microsoft uses the SMB protocol to implement the Common Internet File System, or CIFS, to share files across Windows-based networks.
The next few protocols all deal with email. When you send an email to someone, you’re using Simple Mail Transfer Protocol, or SMTP, which goes out port 25.
When you receive an email, there are two protocols that come into play.
The first is Internet Message Access Protocol, or IMAP, which uses port 143 and allows you to access email while keeping it on the email server instead of downloading it
locally to your computer before you can read it. IMAP is what allows you to access
the same email on different devices. Post Office Protocol version 3, or POP3, is also
used to receive emails and goes with port 110. Instead of storing it on the server, an
email needs to be downloaded to the local computer first before you can access it.
Once an email is downloaded, it’s immediately removed.
9. DNS
Let’s take a look at some of the common networking protocols now.
First is the Domain Name System, or DNS, which runs on port 53.
DNS is responsible for matching hostnames to their IP addresses and vice versa.
So for example, when you type ww.testout.com into your web browser, the DNS server is responsible for translating that into the TestOut web server’s corresponding IP address.
10. DHCP
Dynamic Host Configuration Protocol, or DHCP, is used to assign network devices their IP configurations when they connect into a network. When a client connects, the DHCP request is sent on port 67 to the DHCP server. It sends the IP configuration
back to the host using port 68.
11. SNMP
Next, we have Simple Network Management Protocol, or SNMP, which uses ports 161 and 162. SNMP is used for network management and networking device monitoring—things like firewalls, switches, printers, workstations, or essentially any networked device. When you utilize SNMP, an SNMP manager is typically installed on the server, and an SNMP agent is installed on each host device to gather information about those devices. When the manager needs to talk to the agent, port 161 is used. When the agent sends an alert to the manager, it happens from port 162.<br>
12. LDAP
On a network, we need somewhere to store
usernames, passwords, computer accounts, and other important user and device information.
This is all stored in a directory service, such as Microsoft’s Active Directory. Lightweight Directory Access Protocol, or LDAP, is what accesses this information with port 389.
LDAP is an open-source, vendor-neutral protocol, so it can work with other directory services—not just Active Directory.
The last two protocols are the ones you probably use the most. HyperText Transfer Protocol, or HTTP, and HyperText Transfer Protocol Secure, or HTTPS, are what we use to transfer hypermedia.
The most common use of these protocols is to transfer web pages across the internet with hyperlinks. HTTP uses port 80 and has no encryption, so it’s very unsecure. HTTPS does the same thing, but it uses port 443 and encrypts all communication with TLS.
13. Summary
That’s it for this lesson. In this lesson, we looked at many of the most common ports and protocols you’ll come across. For example, there are remote connection
protocols like RDP, email protocols like IMAP and SMTP, and networking protocols like DHCP or LDAP. It’s extremely important to know and understand each of
them quite well, as they’re fundamental to getting to the bottom of any network communication issues you’ll run into.