Error is the deflection of an obtained result from the expected or true results of an experiment. This happens due to the uncertainty associated with the measurement. Errors can be expressed in absolute or relative terms. While absolute error is the difference between the measured and the true value, the relative error is the percentage of absolute error to the actual value. Errors can be classified based on the source, magnitude, and sign into systematic, random, and gross errors. Systematic errors are reproducible as they originate from defective equipment, flawed experiment design, and personal bias. Random errors arise from uncontrollable variables in the measurement, making them irreproducible and randomly scattered around a central value. Gross errors occur due to human mistakes and are of larger magnitude. Systematic errors can be detected and minimized by using standard reference materials, independent analysis, blank determinations, and varying the sample size.