Startups and small companies need money to grow. Usually, they do not have access to equity markets and try to find another source of investment.
Angel investor is a person who invests money into an early-stage startup. They are also called business angels, angel funders, seed investors, private investors or informal investors.
In return for the invested money, an angel investor gets a company share. Usually an angel investor invests less money than a venture capitalist. An angel investor could be a family member or a friend. Sometimes angel investors create groups to invest more into bigger projects.