A tag for questions that may not necessarily have a clear-cut right or wrong answer and are often subjective. If it's not a bug, feature-request or request for assistance, it is probably a discussion.
This tag is used for questions that ask users to — what else? — discuss an idea, concept or problem. Common use cases include hashing out how the community should handle a certain action and collaborating on how to solve a perceived issue within the community.
A discussion question may not necessarily have a clear-cut right or wrong answer and is often subjective. On Meta, do not use community-wiki mode for subjective topics unless you are asking a "poll" question. Keep in mind, "poll" type questions are discouraged.