Initial Coin Offering. Like an IPO but not quite, you're not selling securities after all, and they may not pay any dividends, you're simply selling a token you can trade with others that may be exchanged for a service by the company that provided them later on. I expect them to raise a lot of uncomfortable questions in a near future.
Coinbase published results of some legal research on ICO legalities. They say tokens that can be exchanged for services are relatively safe. Some ICO tokens actually pay dividends, and that's a little dicier.
There are various other criteria. If it's a fully automatic system already deployed on the blockchain, that's lower risk than a coin whose value depends on company performance.
