ICD-10-CM (Diagnosis Coding):
  Used by: all settings (inpatient and outpatient)
  Purpose: WHY patient was seen / treated
  Format: A00.0 to Z99.89 (up to 7 characters)
  Updated: October 1 each year

CPT (Current Procedural Terminology):
  Used by: outpatient, physician office, ASC
  Purpose: WHAT procedure was performed
  Format: 5-digit numeric codes (10000-99499)
  Category I: main procedures | Category II: quality | Category III: emerging tech
  Updated: January 1 each year (AMA publishes)

ICD-10-PCS (Procedure Coding System):
  Used by: inpatient hospital ONLY
  Purpose: WHAT procedure was performed (inpatient)
  Format: 7 alphanumeric characters (always 7)
  Structure: Section + Body System + Root Operation + Body Part + Approach + Device + Qualifier
  Updated: October 1 each year

HCPCS Level II:
  Used by: all settings, especially for supplies and DME
  Purpose: supplies, equipment, drugs, ambulance not in CPT
  Format: Letter + 4 digits (A0000-V5999)

EXAM FORMAT (current — verify against aapc.com before relying on this for exam-day planning, since AAPC has changed this format before):
  100 multiple choice questions
  4 hours total time
  Open book: current-year ICD-10-CM, CPT, and HCPCS Level II codebooks allowed
  Passing: 70% (70/100 correct)
  Cost: $399 (AAPC member) / $499 (non-member); membership required to register

QUESTION DISTRIBUTION:
  AAPC does not publish an exact fixed question count per domain for the current
  100-question format — treat any specific per-domain number as unverified.
  Directionally, the exam still weights CPT (especially E/M and surgery) and
  ICD-10-CM most heavily, with smaller shares for HCPCS, medical terminology/
  anatomy, compliance, and reimbursement — confirm current domain weighting
  against AAPC's official exam content outline before building a study plan
  around specific numbers.

STRATEGY:
  Tab and highlight your codebooks before exam
  Time management: under 2.5 minutes per question on average (4 hrs / 100 Q)
  Skip complex questions, return later
  Never leave blank — guess if needed (no penalty)
  Practice with current-year AAPC practice exams matching the current format

THREE SYSTEMS: ICD-10-CM (dx) + CPT (outpatient proc) + ICD-10-PCS (inpatient proc)
HCPCS II: supplies, DME, drugs — use when no CPT code exists

CPC EXAM: 100 Q, 4 hrs, open book, 70% passing (verify against current AAPC guidance — this format has changed before)
BOOKS ALLOWED: bring tabbed and highlighted current-year codebooks
TIME: ~2.4 min/question average — skip hard, return later

CODING ORDER: principal/first-listed dx first, then additional dx
SPECIFICITY: always code to highest level of detail (most characters)