An angel investor (also known as a business angel, informal investor, angel funder, private investor, or seed investor) is an individual who provides capital for a business start-up, usually in exchange for convertible debt or ownership equity. Angel investors usually give support to start-ups at the initial moments (where risks of the start-ups failing are relatively high) and when most investors are not prepared to back them. A small but increasing number of angel investors invest online through equity crowdfunding or organize themselves into angel groups or angel networks to share investment capital, as well as to provide advice to their portfolio companies. Over the last 50 years, the number of angel investors has greatly increased.