Hospital admission occurs when a patient is formally registered to stay in a hospital for treatment, observation, or surgery—becoming an 'inpatient' rather than someone just visiting for an outpatient appointment or emergency room treatment. Admissions are an important healthcare metric: governments track admission rates, average length of stay, and wait times for admission to understand healthcare system performance. When hospitals are at or over capacity, they may face 'admission gridlock,' where emergency patients wait on stretchers because no beds are available. Healthcare budgets must anticipate admission volumes, as inpatient care is one of the most expensive components of the healthcare system.