How IT Happened is a science-based odyssey from the beginning of the Universe through fourteen billion years of its history. With side-trips into the sciences behind, and scientific proofs of the relevant underlying theories, the reader is led through the formation of stars, galaxies, and planets; one of the multi-quintillions of which is our Earth. It then moves through the major steps in Earth's maturation that formed oceans, landmasses, an atmosphere, and all of the ingredients needed to initiate the phenomenon of life. Next, it highlights the intimate connection between human beings and the Cosmos, wherein elements formed within ancient stars become the constituent atoms of the first life form. Following is the evolution of that first live being into the subsequent plant and animal species that culminates in speaking, writing, worshiping, clothed, civilized beings. The journey finally concludes with a prognosis for the distant future of the Earth, its occupants, and the Universe itself.