GST is an indirect tax levied on the supply of goods and services. It replaced multiple taxes and aimed to create a single, unified Indian market. Key features include being levied at each stage of supply, providing input tax credit, and having different rates for CGST, SGST, and IGST. Registration is required if certain turnover thresholds are exceeded. Taxpayers must follow procedures for registration, cancellation, and amendments. Input tax credit can only be claimed within prescribed time limits and by following invoice requirements.