Classification of goods governs tariff treatment using HS, hierarchical notes and sequential application of GIR to determine headings. Classification assigns commodities to headings, subheadings and tariff items using HS-compatible codes and national eight-digit extensions; it depends on Section/Chapter/Subheading texts and the General Rules for Interpretation applied sequentially to determine the most specific description or essential character, with reliance on WCO Explanatory Notes, periodic HS amendments, tariff advice, and binding advance rulings to ensure uniform tariff treatment.