Extreme Programming Explained: Embrace Change

This was probably a big deal when it came out but I graduated in 2015 and every job I've had follows most of this stuff already. It's talked about like something that'll blow your mind once you grok it but I think the whole industry has already grokked this book. It did help me understand why no one understands what product we're building and how it mostly doesn't matter because it's ‘agile' to iterate and as long as it's better this year than last year we're all gonna keep our jobs.