How to configure the discussion settings in WordPress
To configure and manage the discussion settings, log in to the admin panel and go to Settings menu>Discussion sub-menu. The settings are mainly connected with comments and comment moderation.
The first group of options on the Discussion Settings page is labeled Default article settings. The option Attempt to notify any blogs linked to from the article is enabled by default. This means that when in a post on your site you put a link to a post on another site, a comment is submitted to the post on that other site; the comment contains a link to your post. If you want your own site to accept such notifications keep the option Allow link notifications from other blogs (pingbacks and trackbacks) enabled. It's enabled by default. Another option in this group is Allow people to post comments on new articles. It's enabled by default and so all new posts that you create are open to comments. If you want to disable comments, unmark this checkbox. Note that this option can be overridden from the settings of each individual post.
The next group with options is Other comment settings. The setting Comment author must fill out name and e-mail is enabled. In this way visitors/unregistered users have to type an email address and name in the respective fields on the frontend each time they want to submit a comment. The next option is Users must be registered and logged in to comment and it's disabled by default. This means that unregistered users are allowed to submit comments. The option Automatically close comments on articles older than is also disabled by default. In this way no matter when the article was published it's open to comments. If you want posts to be closed for comments after a certain time, mark this checkbox and type the period in the respective text field (it's in days).
The setting Enable threaded (nested) comments is enabled by default. In this way when a user replies to a particular comment (there's a reply link under each comment) that reply is displayed on the frontend slightly to the right to indicate it's a reply to the other comment. That option also has a drop-down menu from which you can select how many levels deep can replies go. The checkbox Break comments into pages is unmarked by default. This means that all comments to a post a displayed on the frontend on the same page. If you want to break them into pages, mark this checkbox. In the text field you can type the number of comments per page (50 by default), and from the drop-down menus you can select how the comments should be ordered on each page.
The next settings group on the Discussion Settings screen is E-mail me whenever. The checkbox Anyone posts a comment is marked by default. This means that each time a comment is submitted to a post, the author of that post is notified via email. The checkbox A comment is held for moderation is also marked by default; when a comment is held for moderation an email is sent to the email address of the blog (the one configured from Settings menu>General sub-menu).
The next group with settings is Before a comment appears. The checkbox An administrator must always approve the comment is unmarked by default. If you want each comment to be held for moderation before it's displayed on the frontend, mark this checkbox. The option Comment author must have a previously approved comment is enabled by default. In this way the first comment of an unregistered user is held for moderation.
From the Comment Moderation section on the Discussion Settings screen you can control which comments are held for moderation. There's a text field in which you can specify how many links are allowed in a comment. In the big text area you can list words, IP addresses, email addresses and URLs. If any of the listed items is encountered in a comment, it's put in the moderation queue. When you list them in the text area put one word, IP address, email address, or URL per line.
The Comment Blacklist text area functions in exactly the same way. The difference is that comments are marked as spam.
The last section on the Discussion Settings screen is Avatars. From the settings in that section you can choose whether avatars should be shown or not on the frontend. You can set the maximum allowed rating of avatars/gravatars, and you can select a default avatar for users who don't have their own avatar.
After you're done with the settings don't forget to click on the Save Changes button at the bottom.
For more details check out the tutorial on how to manage the discussion settings in WordPress.