Definitions of taxable supply and territorial location clarify GST scope and registration, input credit and tax measurement rules. The Act provides a detailed glossary that fixes the scope of GST by defining persons and places subject to levy, key supply concepts (including taxable, exempt, composite and mixed supplies), and measures of tax liability such as aggregate turnover, output tax and consideration. It sets territorial rules via definitions of taxable territory, location of supplier and recipient, and identifies registrable categories and business structures relevant for registration, input tax credit, and compliance.