What is comment screening?
On the Personal Info edit screen, you can set your personal or community journal to screen comments from no one, from anonymous commenters, or from users not on your friends list. On your comment page, you will see a link "Screened Comment" if someone's comment has been screened. By clicking the link, you can view the comment, and then, based on whether it is offensive or not, you may click the eye icon to unscreen it or click the red X to delete it. If you choose not to screen any comments by default, you may still screen an individual comment by clicking the eye with the red line through it. It will then be hidden from everyone excepting you and the poster. Either party will need to be logged in to see the screened comment. A screened comment may be deleted by the poster, once again, assuming they are logged in. Community owners may screen individual comments logged into the maintainer's account, and users posting to a community may also screen comments to their post.
There is not yet a way to screen or unscreen individual users via the admin console.
With many thanks to SuperSat.
This is a first draft; bring the edits.