An Ordinal Scale is used to measure things by ranking and doesn't necessarily imply equal distances between the rankings. Medals in the Olympics (Gold, Silver, Bronze) and socioeconomic status (upper, middle, lower) are examples of ordinal scales. For example, you are rating which ice cream flavor out of three (chocolate, vanilla, and strawberry) you like best. You love chocolate but only like vanilla and strawberry a little bit. Using an ordinal scale, your rankings would be 1) chocolate, 2) vanilla, and 3) strawberry although the distance between chocolate and vanilla is much larger than the distance between vanilla and strawberry.
See also: Ordinal Variable