Definition of service clarifies taxable activities, exclusions, and establishment rules shaping service tax liability. The Chapter defines core concepts governing service tax: service (activities for consideration, with specified exclusions), taxable service, assessee, goods, and taxable territory. It links sectoral terms (for example, works contract, renting, information technology software, goods transport agency) to existing statutes, mandates that undefined terms adopt meanings from the Central Excise Act where applicable, and treats establishments, branches, and unincorporated associations as distinct taxable entities for territorial and liability purposes.