Absolute error is a measure of the difference between a measured value and the true value. It is calculated by taking the absolute value of the difference, which means it does not consider whether the measured value is higher or lower than the true value. For example, if the true value of a length is 10 cm and the measured value is 8 cm, the absolute error is |10 - 8| = 2 cm. This concept is important in fields like science, engineering, and statistics, where precise measurements are crucial. Understanding absolute error helps in assessing the accuracy of measurements and improving methods to reduce errors in future experiments or calculations.