A commonly used model for thinking about social classes in the U.S. attributes the following general characteristics to each tier: the upper class has vast accumulated wealth and significant control over corporations and political institutions, and their privilege is usually inherited; the corporate elite consists of high-salaried stockholders, such as corporate CEOs, who did not necessarily inherit privilege but have achieved high status through their careers; the upper-middle class consists of highly educated salaried professionals whose occupations are held in high esteem, such as lawyers, engineers, and professors; the middle class (the most vaguely defined and largest social class) is generally thought to include people in mid-level managerial positions or relatively low status professional positions, such as high school teachers and small business owners; the working class generally refers to those without college degrees who do low level service work, such as working as a sales clerk or housekeeper, and includes most people whose incomes fall below the poverty line.