An initial coin offering (ICO) is a fundraising mechanism in which companies sell digital tokens to investors in exchange for capital, often using blockchain technology. ICOs allow for direct investment into projects without the need for intermediaries, increasing accessibility and attracting a global audience, but they also come with regulatory scrutiny and potential risks of scams. Various types of ICOs exist, including public and private offerings, as well as security and utility token guidelines, emphasizing the importance of thorough research and transparency before investment.