nitty-gritty
Pronunciation:
/ˌnɪtiˈɡɹɪti//ˈnɪtiˈɡɹɪti/noun
Definitions
(originally United States) The core or essence of something; the details.
Example: He gave a short summary without getting into the nitty-gritty of the problem.
Synonyms:brass tacksnuts and bolts