A microscope is a scientific instrument that makes tiny things look much bigger so you can see details invisible to the naked eye. When you look through a microscope at a drop of pond water, you might discover dozens of microscopic creatures swimming around, creatures that were completely invisible just moments before.

Most microscopes use curved pieces of glass called lenses that bend light in special ways to magnify whatever you're examining. A basic school microscope might make something look 40 or 100 times bigger, but powerful research microscopes can magnify things thousands of times.

Microscopes revolutionized science. Before their invention in the late 1500s, people had no idea that bacteria, cells, or tiny organisms even existed. Once scientists could see these microscopic worlds, they discovered how diseases spread, how plants grow, and how our own bodies work at the cellular level. Today, scientists use microscopes to study everything from the structure of insects' eyes to the shapes of individual molecules.

When someone examines something very carefully, we might say they're putting it under a microscope or giving it microscopic attention, even if no actual microscope is involved.