The DELF diplomas are issued by the French Ministry of Education to prove the French-language skills of non-French people. These diplomas are valid for life and recognized worldwide !
There are six independent diplomas, which correspond, respectively, to the six levels of the Common European Framework of Reference for Languages (an international benchmark to evaluate the level of proficiency in a language) : A1, A2, B1, B2, C1, C2.
DELF-DALF diplomas are for example required for the entry in the Higher Education in France (B2 or C1 level).