In his new book, Gates explains why investments like making concrete "greener" will prevent extreme climate change.
The Gates Foundation is helping match vaccine developers with manufacturers to help distribute a COVID-19 vaccine equitably.
The disease affects over 5 million Americans and has no cure.
Gates also spoke to us about the future of energy innovation and clean tech.
The tech giant says "ruthless" private business thinking is necessary for energy innovation.
A weird way to keep track of productivity...