Should the day come when intelligent machines not only make computations but also think and experience emotions as humans do, how will we distinguish the "human" from the "machine"? This introduction to artificial intelligence -- and to its potentially profound social, moral, and ethical implications -- is designed for readers with little or no technical background. In accessible, focused, engaging discussions, physicist and award-winning science writer Thomas Georges explores the fundamental issues: What is consciousness? Can computers be conscious? If machines could think and even feel, would they then be entitled to "human" rights? Will machines and people merge into a biomechanical race? Should we worry that super-intelligent machines might take over the world? Even now we continue to put increasingly sophisticated machines in control of critical aspects of our lives in ways that may hold unforeseen consequences for the human race. Digital Soul challenges all of us, before it's too late, to think carefully and rationally about the kind of world we will want to live in -- with intelligent machines ever closer by our sides.