"Building Social Business: The New Kind of Capitalism That Serves Humanity's Most Pressing Needs" by Muhammad Yunus introduces the concept of social business, which aims to tackle social issues through financially sustainable enterprises. Unlike traditional profit-driven businesses, social businesses prioritize solving problems such as poverty, education, and health. Yunus provides examples of successful ventures, like Grameen Bank, to illustrate how this model works. The book advocates for a shift in capitalism to focus on human needs and social impact, proposing that businesses can and should be a force for positive change in the world.