Moderation refers to two possible changes in a node's status:
Any user-posted root node is subject to moderation. This means, for example, any question posted to Seekers of Perl Wisdom, or a new Meditation.
When a user-posted root node is first created, it is in an unapproved state. This means it will not be listed amongst the approved nodes for its section, nor will it be listed on the Front Page. (Whether a user can see a section's unapproved posts is controlled by a preference setting.)
Once a user-posted root node has been approved into its section,
it will be listed in that section visible to all users.
When a user-posted root node has been both approved and front-paged, it will be listed amongst the approved nodes in its section and it can be listed on the Front Page.
Note that a node cannot be "front-paged but unapproved". With regard to moderation, there are only three possible states for a node:
For Anonymous Monks, and those registered users who have elected not to see unapproved posts, each section's main page will list only approved posts. It is possible for registered monks to change their user settings so as to see both approved and unapproved posts in each section. (Even then, they will be listed separately.) Registered monks should read Miscellaneous Settings for details on how to make unapproved content visible.
Note that all nodes are eligible to be listed on the Newest Nodes page, irrespective of any moderation status. In this way, unapproved nodes are still visible by users who cannot otherwise see unapproved content.
Next: How do I moderate?