Initial Coin Offering means that someone offers investors some units of a new cryptocurrency or crypto-token in exchange against cryptocurrencies like Bitcoin or Ethereum. Since 2013 ICOs are often used to fund the development of new cryptocurrencies. The pre-created token can be easily sold and traded on all cryptocurrency exchanges if there is demand for them.
Many view ICO projects as unregulated securities that allow founders to raise an unjustified amount of capital, while others argue it is an innovation in the traditional venture-funding model.
Several projects used a crowdsale model to try and fund their development work in 2013. Ripple pre-mined 1 billion XRP tokens and sold them to willing investors in exchange for fiat currencies or bitcoin. Ethereum raised a little over $18 million in early 2014 — the largest ICO ever completed at that time.