## High Cardinality

Friend or Foe?

In mathematics, cardinality is the measure of the number of elements (distinct values) of a set. For example, the set `{200,404,503}`

contains 3 elements so the cardinality of it is 3. But what does “High Cardinality” have to do with (time series) metrics?
Glad you asked, the answer is *everything*. :)