What is initial coin offering?
An Initial Coin Offering is a fundraising source from crowd of cryptocurrency investors and markets. When a new currency is launched, the company needs initial funds to make it work and this is where ICO evolved.
The first ICO was by Mastercoin in 2013 which has raised approximately US$6lakh to create Bitcoin exchange.
More info on How does ICO works completes here: https://goo.gl/W1EcdA