This document provides an overview of hearing impairments, including definitions, anatomy of the auditory system, classifications and measurement of hearing loss, characteristics and assessment of individuals with hearing impairments, educational approaches, services, family and diversity issues, technology, and trends. Key points covered include the definition of various types of hearing loss, how sound is processed through the ear, common causes and classifications of impairment, importance of early identification and intervention, and educational methods including sign language, oralism, and total communication approaches.