ICO is Initial Coin Offering.
it is a method of crowdfunding cryptocurrency projects by raising funds through an ICO campaign and in that a percentage of the coins are sold to those who are investing.
but in reality this is turning into a new method to scam people out of their money. the projects are all bad and they show it as being good to take the money and if you check the history majority of the ICO coins get dumped pretty hard after the release.
Not all ICOs are scams or bad projects. We had some good ICOs in the past.
Many people at this point start to forget that development of Ethereum was funded by an online crowdsale in 2014 as well.
Back in that day ICOs were better. Today market is so saturated that is is hard to find really valuable ICO.