Extreme Programming Explained: Embrace Change

Kent Beck's argument is that the practices that make software reliable — pair programming, test-first, continuous integration, small releases, collective code ownership — are not independent techniques. They reinforce each other, and each one is only robust when the others are present. XP made some of the most consequential shifts in how software is actually built, even when teams never adopt its name: test-driven development is now mainstream, continuous integration is infrastructure, small releases are the default. Read it to see how deeply the bet on short feedback cycles runs, and how much of today's "agile" discourse is a diluted version of the original. Beck writes with discipline and conviction; it is a book about craft, not process.