Never Split the Difference" by Chris Voss is a negotiation guide based on FBI hostage tactics, emphasizing emotional intelligence over cold logic. It argues against splitting the difference, advocating for "tactical empathy" to understand the other side's emotions, build trust, and influence outcomes. Key techniques include active listening, mirroring, labeling emotions, using calibrated questions (how/what), and aiming for "that's right" instead of "you're right".