• "picons" is short for "personal icons". They're small, constrained images used to represent users and domains on the net, organized into databases so that the appropriate image for a given e-mail address can be found. Besides users and domains, there are picons databases for Usenet newsgroups and weather forecasts. The picons are in either or both monochrome UNIX XBM and color XPM formats, plus a GIF format.
• compiled in hopes of helping make cyberspace a more personable place. With them, software and services can be developed to identify persons on the net by face (or, at least, by institution logo) instead of by a cryptic e-mail address. Although this software is still more potential than actual, much already exists (see 6.). The picons databases themselves, of course, are only a first step toward this goal.
• An X-Face is a small bitmap (48 × 48 pixels, black and white) image which is added to a Usenet posting or e-mail message, typically showing a picture of the author's face. The image data is included in the posting as encoded text, and attached with an 'X-Face' header. It was devised by James Ashton.
• It is one of the outgrowths of the Vismon program developed at Bell Labs in the 1980s.
• Face headers work exactly like X-Face, but they are capable of displaying colors (they are just base64 encoded PNG images), and have a hard limit of 998 characters (mail server limitation).
• On Gravatar, users can register an account based on their email address, and upload a digital avatar to be associated with the account.