Colour temperature is a measure of the colour characteristics of a light source, expressed in degrees Kelvin (K). It indicates whether the light appears warm (yellow/orange) or cool (blue). Most colour films and digital sensors are balanced for around 5500K, which corresponds to average daylight conditions. Light sources with lower colour temperatures produce warmer tones, while higher colour temperatures result in cooler, bluer tones. Understanding and controlling colour temperature is essential in photography to achieve accurate colour reproduction, maintain visual consistency, and create the desired mood in both natural and artificial lighting conditions.