To Wit: Twittering

Politicians can have their message of the day, but on the Web, anybody can have their message of the hour -- or the minute.

Short updates on social-networking sites have become a new sort of public writing, the equivalent of text-messaging the Web.

As with texting, conciseness matters here; one popular site even limits updates to 140 characters. (See, this paragraph just hit that mark.)

The best-known example of the genre may be Facebook's "status update," in which you can share your latest tidings with friends.

For many Facebook users, it's their favorite part of the site, both reality-show entertainment and creative outlet.

These updates can be mundane, such as recaps of travel (everybody likes to complain about security lines!) and night-life agendas.

They can also be deliberately cryptic, part of the fun of quasi-public speech meant to enlighten close friends and puzzle others.

(What to make of one co-worker's declaration Tuesday that he "doesn't see what the big deal is"?)

Facebook's status updates have plenty of competition at other online social networks, each with its own style and grammar.

MySpace invites you to pick a word to label your mood; the business-networking site LinkedIn lets you describe your current project.

The site to make the most of this concept, however, doesn't offer much but status updates.

Twitter's home page ( http://twitter.com) simply asks people "What are you doing?"