ICO is an abbreviation of Initial Coin Offering. It is a means to collect coins by issuing coins as if issuing stocks, and to develop with the money received. Nowadays, many companies are actively issuing coins, registering them on exchanges, and converting them into cash, which was all unfamiliar before this concept. Listing on the stock exchange is not an easy step, whereas ICO is a smart contract program that issues coins and registers them on the Ethereum network. Anyone can register for a program for ICO, and it serves as a new window to attract investors through white papers, web pages, and community promotions.