United State Medical Licensing Examination (USMLE)
In order to be eligible to enter the US residency programs one needs to pass USMLE Exams.
While USMLE has 3 Steps, it is usually required to pass 3 exams to receive an ECFMG certificate.
USMLE Step 1, USMLE Step 2 CK, and USMLE Step 2 CS.
Passing USMLE Step 3 is not required to get into residency, however, some IMGs prefer to strengthen their profile when they apply by taking it in advance.
USMLE Step 1 mostly involves basic sciencs, USMLE Step 2, however, deals with clinical science. The clinical knowledge is tested in USMLE Step 2 and clinical skills in USMLE Step 2 CS.