Why nominal value differ from measured value of resistors?

Nominal values of resistors are predefined standard values set by manufacturers, while measured values can differ due to tolerances, manufacturing variations, and environmental factors. Tolerances indicate the permissible deviation from the nominal value, which can range from a few percent to higher values, depending on the resistor type. Additionally, temperature, humidity, and aging can affect the resistance, leading to discrepancies between the nominal and measured values.