Laptop
In short
A portable personal computer designed for mobile use that combines a screen, keyboard, and pointing device into a single unit.
In plain words
It is a small computer you can carry around easily. It has a folding design, often called a clamshell, which protects the screen when you close it. You can use it on your lap without needing to plug it into a wall constantly.
A simple example
A student uses a thin laptop in a library to write an essay and browse the internet using the built-in battery.
Why it matters
Laptops allow people to work, study, and communicate from almost anywhere. They provide the power of a full desktop computer in a much more flexible and travel-friendly package.
Easy to mix up
Do not confuse a laptop with a tablet, as laptops usually run full desktop operating systems and have physical keyboards.