Semantic MediaWiki has several built-in datatypes from which one chooses for properties since they are for several reasons very important for evaluating them. For the following reasons, every property used should be defined with a data type:
- The datatype determines how tools should handle the given values, e.g. for displaying values and sorting values in search results.
- The datatype is required to understand which values have the same meaning, e.g. the values "1532", "1,532", and "1.532e3" all encode the same number.
- The datatype sometimes have special behavior, e.g. due to special value conversion.