Session 1: Understanding the Computer

A computer is a machine that takes information in, does something to it, and gives information back. That is the entire idea, and everything else is detail. The input devices are how you tell it things — keyboard, mouse, microphone, camera, scanner. The processing happens inside the system unit or laptop body, on a chip called the CPU. The storage holds your work when the machine is off. The output devices are how it tells you things — the screen, the speakers, the printer.

Why this matters practically: when something goes wrong, you diagnose by asking which of those four stages failed. Is the machine not receiving my input (keyboard problem)? Is it not showing me anything (display problem)? Is my file gone (storage problem)? Is the printer not printing (output problem)? Every troubleshooting method you will ever learn is a refinement of that one question, and it starts here.

A desktop is a computer in separate pieces: a system unit (the box, sometimes called the CPU even though the CPU is a chip inside it), a separate monitor, keyboard and mouse. Its advantages are that it is cheaper for the same performance, easier to repair and upgrade, and better cooled — which is why cyber cafés, offices and schools in Nigeria mostly use them. Its disadvantage is obvious: it stays where it is.

A laptop combines everything into one portable unit with a built-in screen, keyboard, touchpad and battery. It costs more for the same performance and is harder to open, but it is the only option if you need to work in more than one place. Two things about laptops that beginners get wrong: the touchpad replaces the mouse (tap to click, two fingers to scroll, and an external USB mouse works better if you find it fiddly), and the battery is a consumable that degrades — a laptop that only runs when plugged in has a tired battery, not a broken computer.

The system unit (or laptop body) contains everything that does the work. Inside it: the motherboard, the main circuit board that everything else plugs into; the CPU, the processor that carries out instructions — its speed is measured in gigahertz and its generations matter more than its clock speed; the RAM, temporary fast memory that holds what you are working on right now, wiped when power is cut, which is why 8GB is the practical minimum in 2026 and why an unsaved document disappears in a power cut; the storage, either a hard disk drive (HDD, cheaper and slower) or a solid state drive (SSD, faster and the single biggest speed upgrade an old machine can receive); the power supply unit, which converts mains electricity to what the components need; and cooling fans, which matter more in dusty, hot environments than most people realise.

On the outside you have ports, and knowing them saves real time. USB-A is the rectangular port everything plugs into — flash drives, mice, keyboards, printers. USB-C is the smaller oval port on modern laptops, used for charging, data and displays. HDMI carries picture and sound to a monitor, TV or projector — this is the cable you need at any presentation. Ethernet is the network port for a wired internet connection, more stable than Wi-Fi. The 3.5mm jack is for headphones. And on older machines, VGA is the blue trapezoid video port still found on many Nigerian projectors.

Peripherals: the monitor displays output — check its resolution if text looks tiny, that is a setting not a fault. The keyboard and mouse are your input. The printer produces physical copies. Speakers or headphones produce sound. A webcam captures video, built into laptops and usually mounted on top of the screen. A UPS or surge protector is not optional in Nigeria — power fluctuation kills power supplies, and a UPS also gives you the two minutes you need to save and shut down properly.

Turning on is simple: connect power, press the power button, wait. What beginners do not know is that the wait is real work — the machine is loading the operating system from storage into RAM. Interrupting it by holding the power button or pulling the plug is how systems get corrupted. If a machine seems stuck, wait a full two minutes before concluding anything is wrong.

Turning off is where mistakes cost money. Never switch off at the wall socket or hold the power button as your normal method. Use Start → Power → Shut down and wait for the screen to go dark. Shutting down properly lets Windows close files, finish writing to disk and park the drive heads — skipping it is how disks develop bad sectors and how documents get corrupted. Restart is different from shut down and is the correct fix for most odd behaviour, because it clears RAM completely. Sleep keeps your work in memory using a little power and wakes instantly; Hibernate writes memory to disk and powers off fully. In a place with unreliable electricity, hibernate is safer than sleep.

After login you see the desktop: the working surface. On it sit icons, which are shortcuts — pictures representing programs, files or folders. Double-click an icon to open it. The taskbar runs along the bottom and shows every program currently open, plus the clock, the network and volume indicators, and the notification area on the right. The Start menu (Windows key, or the Windows button at bottom-left) is where every installed program lives and where the search box is — typing a program name into Start search is faster than hunting through menus.

A window is a program's own rectangle on screen. Every window has the same three controls top-right: minimise (dash) hides it to the taskbar without closing it, maximise (square) fills the screen, and close (X) quits the program. Drag the title bar to move a window; drag its edges to resize. Alt+Tab switches between open windows and is the single most useful keyboard shortcut in Windows. Windows key + D shows the desktop by minimising everything. If a program stops responding, Ctrl+Shift+Esc opens Task Manager, where you can end the stuck task without restarting the machine.