ADDIE captures a systematic approach to instructional design. It consists of five interrelated components: Analysis, Design, Development, Implementation, and Evaluation. It is a process, as well as a model that can be used for any kind of learning, and allows for opportunities for continuous reevaluation of instructional goals and design at any stage. Because the five phases are interrelated and that changes in one phase influence other steps, it is crucial that the Analysis phase (and Design phase) is carried out comprehensively. Since ADDIE model is not iterative, if any work produced does not meet client/training requirement and assumptions, the task needs a significant amount of reworking/revision.
Here's a quick mind map that I made using mindmeister (https://www.mindmeister.com/) that shows each phase of ADDIE process and action points that need to be taken at each stage.
This webinar on Youtube (https://www.youtube.com/watch?v=WrGbgD8NJUQ ) summarizes key steps of each ADDIE phase.