Theorists Frank Knight and Peter Drucker defined entrepreneurship in terms of risk-taking. The entrepreneur is willing to put his or her career and financial security on the line and take risks in the name of an idea, spending time as well as capital on an uncertain venture. However, entrepreneurs often do not believe that they have taken an enormous amount of risks because they do not perceive the level of uncertainty to be as high as other people do. Knight classified three types of uncertainty:
Entrepreneurship has been described as the "capacity and willingness to develop, organize and manage a business venture along with any of its risks in order to make a profit." While definitions of entrepreneurship typically focus on the launching and running of businesses, due to the high risks involved in launching a start-up, a significant proportion of start-up businesses have to close due to "lack of funding, bad business decisions, an economic crisis, lack of market demand, or a combination of all of these."