HOW many times in life must we engage in self-description? Let us count the ways: There’s the anxiety of college applications. The ignominy of Match.com dating. The embroidery of a C.V. sent to prospective employers. And, of course, there is Facebook.

The profile page of every Facebook acolyte has an enticing little Info tab, presenting the opportunity to demonstrate wit or wisdom, bravado or timidity, personal agenda or professional bona fides. A few categories are suggested by default  Likes and Dislikes, Favorite Quotations  but there’s a big yawning hole in the section labeled Bio. There’s no pull-down menu: the format is fill in the blank, every man for himself.

“It’s unnerving to sum yourself up and convey your personality,” said Gretchen Rubin, a former lawyer in New York and author of “The Happiness Project,” who opted for tongue-in-cheek: Red-haired, left-handed, legally blind, massive consumer of Diet Coke.

“I decided that if you don’t go deep, you might as well go very surface,” she said. “I wrote what I thought stuck out about me, although it doesn’t say that I’m a constant hair-twister.”