Ceremony is a ritualistic or symbolic activity, performed on well-defined occasions. In Agile Development, ceremony is referred to as the core Scrum activities such as sprint planning, daily scrum, sprint review, and sprint retrospective. Ceremony is also defined as a Scrum practice that involves taking action or performing a process, for example, sprint-planning activity, daily scrum activity, sprint review activity, and sprint retrospective activity. In general all these activities are the work performed by the Scrum team members such as writing code, performing tests, creating estimates, and so on.
Meetings, or “ceremonies” are an important part of agile development. A number of these ceremonies come from the practice of scrum which is an iterative, time-boxed approach to implementing agile. The concepts behind these ceremonies can be applied to other forms of agile like kanban or lean.
Book: Agile and Iterative Development: A Manager’s Guide by Craig Larman
Book: Agile Application Lifecycle Management: Using DevOps to Drive Process by Bob Aiello, Leslie Sachs