A deductible in health insurance is the initial amount that policyholders must pay out of pocket for covered medical expenses before their insurance provider begins to contribute. It serves as a cost-sharing mechanism, with policyholders responsible for meeting the deductible before their health insurance coverage fully kicks in. Deductibles can vary based on the insurance plan and can be set annually or per individual. Choosing a higher deductible typically leads to lower monthly premiums, while a lower deductible usually results in higher premiums. Understanding deductibles is essential for individuals to manage their healthcare costs and make informed decisions about their insurance coverage.