An Initial Coin Offering (ICO) is a fundraising method used by startups to raise capital for new cryptocurrency projects. In an ICO, a company sells a new digital token to investors in exchange for established cryptocurrencies like Bitcoin or Ethereum. These tokens often represent a stake in the project or provide access to its services once launched. ICOs gained popularity in the cryptocurrency space due to their potential for high returns. However, they also carry risks, as many projects may not succeed or could be fraudulent. Investors should conduct thorough research before participating in any ICO to understand the project's viability and risks involved.