The United States Preventive Services Task Force (USPSTF) is an independent, volunteer panel of national experts that makes evidence-based recommendations about clinical preventive services including screenings, counseling, and preventive medications. USPSTF grades recommendations A through D and I: Grade A (strongly recommended — high certainty of substantial net benefit), Grade B (recommended — high certainty of moderate or moderate certainty of moderate-to-substantial net benefit), Grade C (selectively offer — small net benefit, individualize based on patient circumstances), Grade D (recommend against — no net benefit or harms outweigh benefits), and Grade I (insufficient evidence to assess balance of benefits and harms). The ACA requires insurance coverage of Grade A and B recommendations without cost-sharing. Key screening concepts include: lead-time bias (screening appears to improve survival by detecting disease earlier, even if death occurs at the same time), length-time bias (screening preferentially detects slow-growing cancers that have a better prognosis), overdiagnosis (detecting conditions that would never have caused symptoms or death during the patient's lifetime), and the Wilson-Jungner criteria for effective screening programs (suitable condition, accepted treatment, facilities available, recognizable latent...