Using World Bank data, the note defines the Base of the Pyramid population as the 4.76 billion people living on less than $10/day. It briefly reviews the perspectives of key business articles that address this market, notably C.K Prahalad's work on Bottom of the Pyramid, and Porter and Kramer's article on Creating Shared Value. The note then provides a somewhat more extensive (yet brief) review of the literature from Development Economics literature, before turning to the perspective offered by the HBS, MBA, course on Business at the Base of the Pyramid (BBOP). The note concludes with a brief statistical tour of the key needs that characterize this market segment, namely: Nutrition, Healthcare, Education, Sanitation, Clean Water & Energy, Financial Inclusion, and Affordable Housing.