An error is a mistake or something done incorrectly. When you add 47 plus 38 and get 75 instead of 85, that's an error in your calculation. When a baseball player tries to catch a fly ball but drops it, the scorekeeper records an error. When you accidentally write “their” instead of “there,” that's an error.

Errors happen to everyone, from students learning multiplication to scientists conducting experiments to professional athletes playing in championships. Scientists actually expect errors in their measurements and plan for them, which is why they repeat experiments multiple times. Computer programmers know their code will contain errors (they call them bugs), so they test thoroughly to find and fix them.

Some errors are small and easy to fix, like erasing a wrong answer. Others are more serious, like an error in judgment that leads to a poor decision. The phrase trial and error describes learning by trying different approaches, making mistakes, and figuring out what works.