Run-Time errors are ones that crash your programme. The programme itself generally starts up OK. It's when you try to do something that the error surfaces. A common Run-Time error is trying to divide by zero. In the code below, we're trying to do just that:
The program itself reports no problems when it is started up, and there are no coloured wavy lines. When we click the button, however, we get the following error message:
Had we left this in a real programme, it would just crash altogether ("bug out"). But if you see any error message like this one, it's usually a Run-Time error.
Look out for these type of error messages. It does take a bit of experience to work out what they mean; but some, like the one above, are quite straightforward.
You'll see how to handle errors like this, soon. But there's one final error type you have to know about - Logic Errors.