What are stages, prerequisites, and choice nodes?

These are the core building blocks of a sequence:

• A stage is a group of items within a sequence that represents a milestone in the learning journey. Each stage can contain one or more items — such as courses, resources or activities. Stages are displayed as columns in the Sequence Builder and generally flow from left to right.
• A prerequisite is a relationship between items that recommends one be completed before progressing to another. Prerequisites guide learners through the recommended path, though learners can still access items independently if they choose.
• A choice node is a branch point where learners pick one of several options to continue. For example, a choice node might say "Pick one: Web Development or UX/UI Design". Completing any one of the choices satisfies the prerequisite for later items in the sequence.