An unregulated means by which funds are raised for a new crypto currency venture. An Initial Coin Offering (ICO) is used by startups to bypass the rigorous and regulated capital-raising process required by venture capitalists or banks. So basically, ICO is sort of like an initial public offering (IPO), but with a crypto twist and without the regulatory difficulties to deal with.
The main purpose of an ICO is that the cryptocurrency venture can create a digital coin or a token which is subsequently offered for sale to the public in an initial offering. You can think of an ICO as a similar process to an initial public offering (IPO) with the main difference that instead of equity share in a company, ICO will grant the investor a new coin or a token. Depending on the structure of the ICO the investor receives the coins for their investment. The more common use case for an ICO is the value they provide to the investor which gives you access to using a specific project or a service. The venture, in turn, uses this money to grow and expand their platform.