An ICO is a popular crowd fundraising mechanism for startup cryptocurrency projects, in which a percentage of the initial token supply is sold to early supporters. ICOs originated with Mastercoin in 2013. Many ICOs use the Ethereum smart contract platform as a protocol to create and sell new tokens under the ERC-20 standard; Ethereum itself was funded through an ICO in 2014. ICOs became particularly popular in 2017 and 2018, where over $20 billion was raised to support development of over 1,000 projects. ICOs are the subject of significant legal controversy, particularly in the United States, as being possible unregistered security offerings. Unlike the similarly-named IPO, tokens sold through ICOs typically do not confer ownership rights or represent equity to the associated company and instead offer a wide variety of usage or utility functions within their associated networks or platforms.