Significant figures

What is the difference between precision and accuracy? Some people use these terms interchangeably.

Assume we have an instrument which shoots darts at a target. We calibrate this instrument to be precise. That is to reproduce the same trajectory for each dart every time. So precision is an indication of how well the machine can reproduce the trajectory for each shot.
Accuracy describes how close each dart is to the target.

This instrument is neither accurate nor precise.

This instrument is both accurate and precise.
This instrument is precise but not accurate.
Continue with significant figures.