Comparing Lean, Agile, and Continuous Delivery

With DevOps and Continuous Delivery gaining traction, are the principles behind Lean and Agile still relevant? How do they compare to the 5 Continuous Delivery principles, and what do any differences mean for software development teams?

The Beginnings of Lightweight Software Delivery

Throughout the 1990s, a revolution was brewing in the software development industry. The early phased models divided the delivery process into skill-based steps, with designs and documents used to run approval processes to control a project.