Existence (Existenz) is for Heidegger a term of art that signifies the kind of being of human beings or of Dasein. Something that exists understands itself in terms of a distinctive possibility: the possibility of deciding to be itself or not be itself (SZ 12). Thus, an existing being is one that is never reducible to its present properties – there is always something about it which is outstanding or which remains to be determined (see SZ 233).