Chapter 3 of the International Building Code establishes the framework for classifying buildings and structures based on their intended use and occupancy. This classification system is fundamental to determining which building code provisions apply to a given structure. The IBC defines 11 primary occupancy classifications: Assembly, Business, Educational, Factory, Hazardous, Institutional, Mercantile, Residential, Storage, Utility, and Parking. Each classification carries specific requirements for construction type, fire-resistance ratings, automatic sprinkler systems, and means of egress. Assembly occupancies include nightclubs, concert halls, and stadiums with unique egress requirements. Business occupancies encompass offices, professional services, and educational offices. Educational occupancies include schools and training facilities with enhanced fire safety measures. Factory and industrial occupancies are divided into moderate-hazard and low-hazard categories. Hazardous occupancies involve storage or processing of hazardous materials. Institutional occupancies include hospitals, nursing homes, and detention facilities with special care considerations. Mercantile occupancies are retail stores and sales rooms. Residential occupancies range from single-family homes to multi-unit dwellings. Storage occupancies are buildings for storing non-hazardous materials. Utility and miscellaneous occupancies include agricultural buildings and low-hazard structures. Mixed-use buildings must meet requirements for the most restrictive classification present. The code requires that occupancy classification be clearly identified on construction documents. Understanding these classifications is essential for code compliance and ensures appropriate safety features are implemented.