There was a time when ICO gained the greatest popularity, and now it is popular too, but more options have come. Whoever wants to raise money for projects can do it through an ICO, and they can get funding for the project in this way. This way, a company can sell its tokens earlier to the people who invest before the project launch. When tokens are listed on the exchange, then these early investors earn profit however, it is not always guaranteed that people get profit from this, so this is risky too, because not every ICO is gonna work for you, but yes, ICOs work for the company owners to gather funds.