Twitter tries to simplify its service

Twitter on Thursday announced a new design for its service that the company hopes will draw in new users, keep them on the site longer and persuade paid advertisers to follow them there.

The new look for Twitter, which is rolling out first in applications for Apple and Android phones, has three new tabs that Twitter hopes will make the service simpler for the uninitiated to use: a personal home page, marked by a birdhouse icon; an "@ connect" tab signifying conversations, people and brands; and a "# discover" tab for keywords and topics. Clicking an old-fashioned quill symbol lets you compose a message.

Jack Dorsey, a Twitter founder and chairman of the board, characterized the new look this way: "Less places to click, less things to learn."

Founded five years as a platform for sending out pithy text-message-like missives, Twitter now has 100 million users worldwide, according to figures from the company. Its audience is a fraction of Facebook's and, on average, younger and more tech-savvy.

Twitter is remarkably easy in some respects. Every message - or tweet - must be limited to 140 characters, including links to Web sites, music or photographs. Or a user can quietly follow others who have something to say - celebrities, politicians or their moms - or read about the issues that are "trending," or popular worldwide.

Twitter is designed for public messages and allows users to sign up using pseudonyms. It has proved to be a remarkably nimble tool in mobilizing protest movements and spreading political messages.

But it has been vexed by a perception that it is difficult to use. Quirks like hash tags, or message topics preceded by an # symbol, can be off-putting to first-time visitors.

Thursday's announcement seems designed to position Twitter as a more mainstream instrument, and presumably to draw more advertisers.

As a symbol of its ambition, Twitter unveiled the new design at its would-be new headquarters: a 215,000-square-foot space in a long-defunct Art Deco-era building in downtown San Francisco. Twitter, which currently employs 700 people in a smaller office space, said it would be able to hold "thousands" of people in its new space.