Definition of Business and Supply clarifies taxable scope and entitlement to input tax credit under state GST. The Act's definitional framework determines taxable scope and compliance mechanics by defining core concepts-business, supply (including composite and mixed supplies), taxable person, registered person and place of supply-and by specifying measurement bases (aggregate turnover, turnover in State), input tax and input tax credit rules, liability-shifting via reverse charge, and administrative terms governing assessment, audit and registration.