How are API's implemented in the CiviCRM Codebase? I have a idea of basic structue user <-> api <-> BAO <-> DAO <-> mysql but I guess there is more to this than just this structure. Thanks in Advance!
Welcome to CiviCRM SE! The first place to look for this information is in the relevant section of the developers guide at https://docs.civicrm.org/dev/en/latest/api/