After the resident completes the required program, he takes a required certification exam.
a.    24 formally certifying boards
b.    Overseen by the American Board of Medical Specialists (ABMS).  ACGME is no longer involved.
c.    The certification process of one of the specialty boards (ABNeurosurgicalS, etc.) is approved by the ABMS.
d.    Physician applies and sends in the certification of residency.  Some residents start this process during residency, and some start after completion of residency program.
e.    You do not have to have the board certification, but it is encouraged and most hospitals require you to have it in order to practice in that particular specialty.
f.    Medicare gives no credit to board certification.
g.    Managed Care Organizations often require board certification and this is seen especially with regard to referrals.