L-functions play a vital role in number theory. These functions arise from arithmetic and geometric objects and their value distribution encodes significant information about the underlying structure. The degree and the conductor are certain invariants associated to L-functions. A classical converse question is to determine how many L-functions are there with a given degree and conductor. In this talk, we discuss this question in the context of general Dirichlet series and highlight its application to the study of families of number fields.