Moodle Quizzes & Question Bank Categories
Question may exist within the question bank without ever creating categories. However, the more questions you add, the more jumbled and disorganized it will become.
Categories are a method of creating organization within your question bank. Each category is like a folder or a 'bag' of questions in a similar topic.
Note: When sharing Moodle quizzes with other teachers/courses, the quiz itself cannot be exported, but the category that the questions for that quiz are in CAN be exported; therefore, categories not only organize your own question bank, but also make collaboration and sharing of resources easier/possible between PLCs.