Kent Beck has been an active industry leader in software technology, known for CRC Cards (with Ward Cunningham), JUnit (with Erich Gamma), TDD, and Extreme Programming. His classic 1999 book “Extreme Programming Explained" was the first book on Extreme Programming. Kent has an active substack - TidyFirst: https://newsletter.kentbeck.com/ - and he continues to share his thoughts in the world of Thinkies: https://newsletter.kentbeck.com/p/thinkie-tutorial.