Definitions: scope of 'business' and 'supply' under Delhi GST determine taxable obligations and territorial application. Section 2 defines core terms that determine GST liability and operation in Delhi: business, supply (including composite and mixed supplies), taxable person, registered person, aggregate turnover, input, input tax and input tax credit. It sets territorial and place-of-supply markers (taxable territory; place of business; location of supplier/recipient), specifies special categories (casual, non-resident, agent, Input Service Distributor), and establishes administrative concepts (invoice, return, assessment, adjudicating and revisional authorities) to govern registration, liability, credit entitlement and enforcement.