A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
designed to solicit opinions or best-practices on a particular topic, with the goal of reaching community consensus.
Use for Meta Questions related to changing tags on existing questions (merge, manual changes, anything basically).
held to choose moderators for Stack Overflow and non-Beta Stack Exchange sites, including Server Fault.
are in reference to a specific question on Server Fault.
Meta-questions which relate to Server Fault being doomed.