wordpress: managing settings
Default article settings: Note that these options relate to the default settings for newly posted articles. You can always override these settings on a per-article basis. Turning them on or off will not affect existing posts in the system - if you want to do that, use the Batch Management tools described earlier.
The first two options relate to "notifications" or "pings." This is a technology through which two blogs discussing the same topic can include links in one another's comment stream. If I link to your blog from one of my posts and we both have notifications enabled, a link to my blog will automatically appear in your post's comments.
Comment author must fill out name and e-mail: This setting is strongly recommended for all sites - allowing anonymous comments makes it much more difficult to keep spam under control.
Users must be registered and logged in to comment: This is a fantastic way to keep spam levels down, but at a high cost: Most users aren't willing to register just for the privilege of commenting. Expect your comment traffic to go way down if you enable this (we don't recommend it). Akismet and other tools (described earlier) are a much better way to fight spam.
Automatically close comments on articles older than xx days: A lot of spam shows up on older articles, while most legitimate comment activity happens on recent articles. You can cut out a lot of spam by simply closing comments on older posts. However, this can be very frustrating to users who happen to stumble across one of your old posts and have something useful to contribute. Again, we don't recommend doing this - there are better ways to fight spam.
The rest of the options in Other Comment Settings are pretty self-explanatory, as are the "E-Mail Me Whenever..." options.
Before a comment appears: Since WordPress knows which commenters you've approved in the past, you can allow it to automatically accept new comments from people who have been previously approved. This setting is highly recommended, but the other one - Requiring administrators to always approve comments -- is a little heavy-handed, we believe.
Comment Moderation: This section lets you give WordPress additional rules about how to determine when a comment should be held for moderation. Since many spam messages include lots of links, WordPress defaults to marking any comment with more than two links as needing moderation. You can change this. You can also establish a set of "stop words" that should automatically trigger either moderation or immediate marking as spam.
Avatars: Years ago, a service called Gravatar let users set up a personal icon/avatar associated with an avatar. When that user left a comment on any blog or site that used the Gravatar plugin, their icon would show up, universal across the web. Automattic later bought Gravatar and integrated it with WordPress. From this panel, you can turn avatars on or off, and protect yourself from avatars that might potentially be offensive, with a movie rating-like system. You can also set the default avatar for users who haven't yet set up their Gravatar.