The four Ds organize product development as a feedback loop: develop a customer-requested change, deliver it, discuss its value with customers, and design the next step. section 1.1
The cycle moves through four connected stages:
- Develop features or changes that address what customers want. section 1.1
- Deliver the manufactured product through an increasingly automated flow. section 1.1
- Discuss the product or feature with customers and use their response as feedback. section 1.1
- Design the next change, restarting the loop with better information. section 1.1
From commit to customer
Treat committed source code as raw material: analyze it, build it, and ship the result as a library to a device or server. Customer discussion then informs the next design. section 1.1
The loop diagram shows how development, delivery, discussion, and design return work to the next iteration. section 1.1
