In measurement and instrumentation, both accuracy and precision are important, but they mean different things. Accuracy is how close a measured value is to the real value of the thing being measured. In other words, it is a way to figure out how well the measuring system can find the right value. A measurement system with high accuracy will give values that are very close to the real value of the thing being measured. Precision, on the other hand, is how consistent a measuring system is when measuring the same thing over and over again. In other words, it is a measure of how well the measuring system can make the same value over and over again. A high-precision measuring system will give you values that are very consistent, even if they are not very close to the real value.
Think of a target with a bullseye in the middle to show the difference. Accuracy is how close a shot is to the centre of the bullseye. Precision is how close together a group of shots are, even if they are not all in the centre of the bullseye.