We've created, appointed, or otherwise identified certain question/answer pairs that are the canonical answer for certain problems. These are answers where the community has said all it is going to say on a class of subject, because although everyone's particular problems in that class are somewhat different, to the extent that they are interesting, they aren't different, and to the extent that they're different, they aren't interesting (to anyone save the questioner). So we write one answer that's designed to be the last word on the subject, and say no more.

A list of these problems is given in the accepted answer below.

Please: