QR codes are widely used in our daily life from social media websites to cash less shopping wallets, ERP (Enterprise Resource Planning) Software implementation to Display advertising and digital marketing etc. This project is divided into five subparts. In first part, we have introduced about basics of QR codes, their versions, creating and scanning process and its various application. Then in second part we have written about various features of QR codes, due to them QR code became so popular and we have also discussed about its structure to understand its basic functionality. There after we have compared three different kinds of codes-bar code, quick response code and color quick response code, based on its storage capacity, error resistance,360 degree reading and other factors. Then in fourth part we have reviewed the literature and mentioned various techniques used by researcher to increase the data storage capacity of QR codes.