GST is a destination based tax consumption of goods and services. It is levied at all stages right from manufacture up to final consumption with credit of taxes paid at previous stages available as setoff. In a nutshell, only value addition is taxed and burden of tax is to be borne by the final consumer.
Currently, a manufacturer needs to pay tax when a finished product moves out from the factory, and it is again taxed at the retail outlet when sold. The taxes levied at the multiple stages such as CENVAT, Central sales tax, State Sales Tax, Octroi, etc. are replaced by GST introduced at Central and State level.