Perl Style: The Art of Commenting Code

Explain what the code does, don't just perl2englishify.
Eschew gaudy block banners.
Use comments in regexes with /x.
Comment entire blocks, not single lines.
`Comments on data are usually much more helpful than on algorithms.' (Rob Pike)
`Basically, avoid comments. If your code needs a comment to be understood, it would be better to rewrite it so it's easier to understand.' (Rob Pike)