Harvard Business Publishing

10. Lists don't take a lot of human attention to process. Since we don't seem to have much to spare these days (particularly online), that makes them popular.

9. Ranked lists imply a comforting order to the universe. People like to believe that some people, teams, or companies are simply better than others. Never mind that it's all about the criteria the rankers use, and the niggling detail that there may be no significant difference between ranks.

8. Lists can be worded tersely. They're easy to write.

7. We've gotten conditioned to the context-free sentences (or even less) in lists, perhaps because of the popularity of bulleted lists in PowerPoint.

6. Lists are popular online because they are amenable to the "slide show" web format, which artificially runs up the page view count. In other words, they help to impress advertisers. Readers hate slide shows, but they seem to be proliferating nonetheless.

5. You can get away with silly statements in the middle of the list, because nobody's reading closely at that point. For example, it's clear to me that lists are to Internet content what Paris Hilton is to acting.

4. Lists are a good way to present jokes. Witness their popularity on Letterman since September 18, 1985 ("The Top Ten Things That Almost Rhyme With Peas" was the first ever).

3. Lists imply that you have exhausted the possibilities for items in them, although the predominance of the decimal system in our society means that you usually have to have ten items. Sometimes that means a need for artificial list fillers or repeats.

2. Lists seem to come in 10's, so be wary of repetition.

1. Particularly when the numbers in the list are in decreasing order, there is an expectation that the number one item will be particularly momentous. Sadly, the last item rarely meets expectations.