An interval scale is a type of measurement scale that not only categorizes data but also establishes a meaningful order and equal intervals between values. This means that the difference between any two values is consistent and can be quantified. A common example of an interval scale is the Celsius temperature scale, where the difference between 10°C and 20°C is the same as between 20°C and 30°C. However, an interval scale does not have a true zero point, which means that zero does not indicate the absence of the quantity being measured. For instance, in the Celsius scale, 0°C does not mean there is no temperature; it simply represents the freezing point of water. This characteristic distinguishes interval scales from ratio scales, which do have a true zero.