ICO is short for First Coin Offering. Consider this similar to buying IPOs. You can pick to buy a new cryptocurrency by paying in Bitcoins as well as Ethereum, and these can be cost a costs on crypto-exchanges when they are introduced as well as if there is a demand for them. This article can aid you recognize better. There are numerous areas where you can track regarding ICOs, you can start here on CoinGecko and also ICO development checklist. There would generally be some minimal amount that you need to invest in ICOs (maybe 1ETH).