A tester is someone who examines or tries out something to see how well it works or to discover problems. When a video game company hires testers, those people play the game over and over, looking for bugs, glitches, or confusing parts before the game gets released to the public. Software testers click every button and try every feature to make sure a program works correctly.

The word can also refer to a small sample of a product that lets you try it before buying. At an ice cream shop, you might ask for a tester spoonful of a new flavor to see if you like it. Some stores have makeup testers so customers can see how colors look on their skin.

In science, a tester might be a tool or device used for checking something: an electrician uses a voltage tester to see if wires are safe, and a chemistry student might use pH tester strips to measure how acidic a liquid is.

Whether it's a person checking a new app or a tiny sample cup of paint at the hardware store, a tester helps you know what you're getting before you fully commit.