Learn in the textbookAgile Development and XP Practices
DefinitionAgile (アジャイル) is a development approach that goes from planning to review again and again in short cycles, growing working software a little at a time.
ExplanationEach short cycle is called an iteration (イテレーション), and every one starts with the features that rank highest at the time. Instead of fixing every specification up front, the team keeps revising the scope while talking with users. Showing something that runs early and getting feedback counts for more than polishing documents in detail.
AnalogyIt is like a trip where you don't plan every minute before leaving, but rework the next day's plan each evening based on the weather and how you feel.
Memory hookThe English word agile means nimble and quick. Picture someone traveling light, with no heavy plan on their back, able to change direction easily.