Our daily lives revolve around numbers, which have a role in practically everything we do. In this Very Short Introduction, acclaimed popular-science author Peter M. Higgins explores the universe of numbers, showcasing its diversity and offering an overview of all the number kinds used in contemporary science and mathematics. Indeed, Higgins creates a clear picture of the universe of numbers, introducing important ideas like integers, fractions, real and imaginary numbers, and complex numbers while demonstrating how the modern number system evolved over many centuries. Higgins illuminates intriguing subjects like the sequence of primes, outlining how primes are currently utilized to secure private data on the internet. The limitless nature of number collections is also explored, and he describes how the so-called real numbers combine to produce the number line’s continuum. Numbers clearly describe the nature of numbers and how so-called complex numbers and number systems are employed in computations that arise in actual problems. It is written in the style of Higgins’ wildly famous scientific paperbacks.