Meanning

SGST:- State goods and service tax When we sell goods in our own state, it is called SGST
CGST:- In this, when we supply the goods at one place like we are in Delhi, we are selling the goods inside it, then whatever tax will be there will be tax paid to the Central Government.
IGST:- integrated goods and service tax In this, when we supply the goods in a different state outside, then inside it, we put the SGST + CGST = IGST paid. In this, the tax has to be paid by a single type, which we call IGST. Central has to be paid tax in this.

charged on

SGST:- state government charged on this tax this is called local tax
CGST:- central goods and service tax this is charged on central government tax its called local tax
IGST:- When we purchase or sell goods in different states from our state in India, then we charge IGST on the transaction of this level, which is collected by the state government. (18%)

Note point :-There are also 2 taxes in IGST, Interstate and Interastate