Difficulty: Beginner | Prerequisites: Computer Basics Overview (Part 1), Hardware Components (Part 2)
Parts 1 and 2 covered what a computer is and the physical hardware it contains. This third set of notes covers the software side (operating systems and applications), how computers connect to each other (networks), and the practical concerns around using computers safely and responsibly: backups, viruses, ergonomics and software copyright. These topics tend to appear on exams as scenario-based or definition questions, so knowing the terminology and being able to give examples is important.
Software divides into operating systems (the foundational layer that starts when you power on) and application software (the programs you use for actual work, such as word processors and spreadsheets). Computers can be networked via LANs (within a building) or WANs (across cities or countries). Protecting your data means regular backups, antivirus software and good ergonomic habits. Software copyright, including the concepts of freeware and shareware, governs how you may legally use programs.
Operating system (OS)
A special program that loads automatically when you start the computer. It acts as the link between the hardware and the user, letting you use advanced features without needing to understand the low-level details of how the hardware works.
In simple terms, the software that runs the show so you do not have to think about bits and bytes.
Application software
Programs you use once the operating system is loaded, to accomplish specific tasks. Examples: word processors (Microsoft Word), spreadsheets (Microsoft Excel), databases (Microsoft Access), presentation tools (Microsoft PowerPoint).
In simple terms, the tools you open to get work done.
LAN (Local Area Network)
A system in which individual PCs are connected together within a single building, office or campus. Allows sharing of printers, scanners and files.
Think of it as a private network inside one location.
WAN (Wide Area Network)
A network that connects computers over a wider geographical area, potentially spanning cities or countries. The internet is the largest WAN.
Think of it as connecting offices (or homes) that are far apart.
Modem
Short for MODulate/DEModulate. A device that sends computer data across telephone lines by converting digital signals to analogue and back again.
Computer virus
A small program that hides on disks and activates under certain conditions. Viruses can spread from one computer to another via infected disks or over a network, including the internet.
In simple terms, malicious software that copies itself and can damage your data.
Backup
A copy of your data stored separately from your main system. Essential because hard disks can fail, and the data on them may represent years of work.
Freeware
Software distributed free of charge. The author retains copyright but allows anyone to use it without paying.
Shareware
Software you can try for free, but you are expected to pay a fee if you continue using it.
RSI (Repetitive Strain Injury)
A condition caused by repetitive movements (e.g. prolonged typing) that can lead to pain in the hands, wrists or arms.
UPS (Uninterruptible Power Supply)
A battery backup device that keeps your computer running briefly during a power cut, giving you time to save work and shut down properly.
A special program that loads automatically at startup
Acts as the link between you and the hardware
Lets you use the computer without understanding low-level technical details
Examples: Microsoft Windows, macOS, Linux
Application programs run on top of the operating system. Common categories:
Word processing – Microsoft Word, Lotus Word Pro, WordPerfect
Spreadsheets – Microsoft Excel, Lotus 123
Databases – Microsoft Access, Lotus Approach
Payroll – Sage software
Presentation tools – Microsoft PowerPoint, Lotus Freelance
Desktop publishing – Adobe Photoshop
Multimedia – encyclopaedia software (e.g. Microsoft Encarta)
LAN (Local Area Network)
Connects PCs within a single organisation or building
Allows sharing of printers, scanners, modems and files
A single printer can serve an entire office of ten people
WAN (Wide Area Network)
Connects computers across wider geographical areas
The internet is the most well-known WAN
Modem
Stands for MODulate/DEModulate
Converts digital signals to analogue for transmission over telephone lines
The receiving modem converts the signal back to digital
At home – games, working from home, online banking, browsing the web
In education – Computer Based Training (CBT) packages on CD-ROM combining text, graphics and sound; ranging from encyclopaedias to language courses
In the office
Automated production systems (computer-controlled robots in factories)
CAD (Computer Aided Design) for producing exact specifications and drawings
Stock control systems that track inventory and reorder automatically
Accounts and payroll processing
In daily life – accounts, games, education, online banking, smart ID cards, supermarkets, tele-working, internet
Take frequent breaks away from the computer
Position screens, chairs and keyboards correctly
Ensure adequate lighting and ventilation
Secure cables safely; do not overload power points
Be aware of RSI (Repetitive Strain Injury), screen glare and bad posture
Computers prefer good ventilation, clean environments and stable surfaces
Avoid dust, eating/drinking over the keyboard, extreme heat or cold, and placing objects on monitors
The most important thing on your computer is your data, not the hardware
Hard disk contents can represent years of work; disk failure means losing it all
Regular backups are essential
Organise files for efficient backup
Understand complete vs incremental backups
Store backups off-site for disaster protection
Use passwords to protect data
Shut down the computer properly to avoid file corruption
Consider a UPS (Uninterruptible Power Supply) to guard against power cuts
Small programs that hide on disks (floppy disks, hard disks)
Activate under specific conditions; you may not know one is present until it triggers
Spread via infected disks or over networks (including the internet)
Prevention: use third-party antivirus software, keep virus definitions up to date
Updates are available on disk or via online download
Freeware – free to use, but the author retains copyright
Shareware – try before you buy; payment expected for continued use
Site licences – allow an organisation to install software on multiple machines under a single agreement
Software found on the internet is still subject to copyright
If your system holds personal data about individuals, you have a moral and legal duty to protect it (data protection laws apply in many countries)
Networking is why everyone in an office can share one printer and access the same files. CAD software is how engineers design car parts and architects draw buildings before anything is physically built. Antivirus software and backup procedures are the reason organisations can recover from ransomware attacks and hardware failures without losing everything.
Students often think the operating system is an application. The OS is the foundational software layer; applications run on top of it. You cannot run Word without an OS already loaded.
"LAN" and "Wi-Fi" are not synonyms. A LAN is any local network, whether wired or wireless. Wi-Fi is one technology for building a wireless LAN.
Students assume that free software found online has no copyright. Freeware is still copyrighted; the author simply permits free use. Downloading pirated commercial software is a separate, illegal matter.
Backing up to the same hard disk does not count as a proper backup. If the disk fails, the backup goes with it. Off-site or external storage is the point.
⚠️ Be able to explain the role of the operating system and give examples.
⚠️ Know the difference between a LAN and a WAN, with a real-world example of each.
⚠️ Understand what a computer virus is, how it spreads, and how to prevent infection.
⚠️ Be able to explain why backups matter and describe different backup strategies (complete vs incremental, off-site storage).
⚠️ Know the definitions of freeware, shareware and site licence.
⚠️ Ergonomics questions may describe a workplace scenario and ask you to identify problems (bad posture, screen glare, no breaks, overloaded power points).
True or false: The operating system is a type of application software. (False, it is system software that applications run on top of.)
Fill in the blank: A ______ connects computers within a single building; a ______ connects computers across wider areas. (LAN, WAN)
True or false: Shareware is always completely free to use permanently. (False, you are expected to pay if you continue using it.)
Fill in the blank: "Modem" stands for ______ / ______. (MODulate, DEModulate)
True or false: Storing your backup on the same hard disk as your original data is a reliable backup strategy. (False, if the disk fails you lose both.)
Q: What is the role of the operating system?
A: The operating system is the foundational software that loads when the computer starts. It manages the hardware, provides a user interface, and allows application software to run without needing to interact with the hardware directly.
Q: Explain the difference between a LAN and a WAN, with an example of each.
A: A LAN connects computers within a single location (e.g. an office building sharing one printer). A WAN connects computers across wider distances (e.g. the internet connecting millions of computers worldwide).
Q: Describe two ways computer viruses spread and one way to prevent infection.
A: Viruses spread via infected floppy disks inserted into a computer and via network connections, including the internet. Prevention: install reputable antivirus software and keep its virus definitions updated.
Q: A company stores customer records on its computer system. What legal obligation does it have?
A: The company has a moral and legal duty to treat that personal information with respect. In many countries, data protection laws require organisations to store personal data securely and use it only for its stated purpose.
Q: Name three good ergonomic practices when using a computer for long periods.
A: Take frequent breaks, position the screen at eye level to avoid neck strain, and ensure the chair supports proper posture with feet flat on the floor.
The software concepts here build directly on the hardware covered in Part 2: the OS loads into RAM from the hard disk, and application software uses the CPU and memory described there. Networking connects to the types-of-computers material in Part 1 (PCs can be standalone or networked to mainframes). Virus prevention and backup strategies also tie back to understanding storage devices from Part 2.
operating system, OS, application software, word processing, spreadsheet, database, LAN, local area network, WAN, wide area network, modem, MODulate DEModulate, computer virus, antivirus, backup, complete backup, incremental backup, off-site storage, freeware, shareware, site licence, software copyright, data protection, RSI, repetitive strain injury, ergonomics, UPS, uninterruptible power supply, CBT, computer based training, CAD, computer aided design, stock control, payroll software, health and safety computing