Explain in the context of CGST Act, 2017 the following: Composition levy

Composition levy is an optional alternative method of levy of tax designed for small taxpayers- Threshold limit viz. aggregate turnover in state of taxable person should not exceed ₹ 75 lakh (or 50 Lakh in special category states) [Limits are as amended upto cut-off date of 30th June, 2017] Rates of composition levy i.e. 2% of turnover for manufacturers, 1% of turnover for traders, and 5% of turnover for restaurants. There are other conditions, which need be fulfilled to avail of composition levy and further, there are restrictions as to input tax credit.