You've probably heard of machine learning, but how does it work, and what does that mean for libraries? In this talk I'll make you laugh - and then think - as we walk through real-world examples. You'll get a high-level overview of how neural nets work and you'll get to explore Hamlet, a prototype library discovery interface based in neural nets. You'll also see why machine learning might NOT be the right tool for your job, due to its limitations, biases, and social risks.