Requirements, Estimation and Planning: Steps to work with Agile software development projects

This article is about requirements, estimation, and planning in agile software development projects.  Agile estimation is often seen as being invaluable, yet others dismiss it as waste. The reasons for this disagreement can be traced to disparities in the Scrum and Lean-Kanban ways of working. Everybody in software development has the same goal: rapid, reliable, low risk delivery of high-quality, valuable functionality to users. So what will help them to achieve their goal? Just coding?