Obstructive sleep apnea (OSA) is a very common and underdiagnosed condition across the world. It affects both pediatric and adult populations in unique but important ways. Long-term health risks associated with OSA include cardiovascular conditions, metabolic disorders, depression as well as poor work performance, and increased risk of motor vehicle accidents. Accurate and precise testing is vital to ensure accurate treatment, and specific testing methods are reviewed. Treatment options are discussed in detail for both adult and pediatric populations.