A billionaire is an individual with a net worth of at least one billion units of currency, typically USD, a concept popularized by Forbes magazine, which tracks them globally. The first confirmed billionaire was American oil magnate John D. Rockefeller in 1916. By March 2025, there were 3,028 billionaires worldwide, with a combined wealth exceeding $16.1 trillion. The vast majority are male, with less than 11% of the 2015 list being women, though female billionaire numbers grew faster (46%) than male (39%) between 2014 and 2019. While education is not universal (nearly 30% of billionaires lack a college degree), top universities like Harvard are heavily overrepresented, and finance and economics are the most common fields of study. The title of world's richest person has fluctuated recently among Jeff Bezos, Bernard Arnault, and Elon Musk.