If you sign up to receive an account's Twitter Alerts, you will receive a notification directly to your phone whenever that account marks a Tweet as an alert. Notifications are delivered via SMS, and if you use Twitter for iPhone or Twitter for Android, you'll also receive a push notification. Alerts also appear differently on your home timeline from regular Tweets; they will be indicated with an orange bell.
The U.S. Federal Emergency Management Agency, Tokyo's Disaster Prevention service and the World Health Organization are among participating agencies who have signed on to Twitter's Alert program.
To subscribe to these notifications, you can go directly to an account's setup page, which you'll find at twitter.com/[username]/alerts.
Currently, a number of organizations in the U.S., Japan and Korea can send Alerts, and we will expand the service to include more public institutions and NGOs around the world.
Twitter to broadcast NFL video clips
In related news, Twitter said on Wednesday it would carry instant-replay footage from National Football League games as part of a new advertising partnership.
Amplify was formally unveiled last May as a way for Twitter, broadcasters and advertisers to capitalize on peoples' use of social media while they watch TV.
Amplify allows broadcasters to show video clips and ads through tweets that are coordinated with what is being shown on TV.
Under the new agreement, the NFL will package in-game highlights and other video content - as well as a short ad from a marketer - inside tweets that are "sponsored" and distributed by the marketer during games.
Verizon is the premiere sponsor for the NFL agreement and has exclusive sponsorship rights for Amplify ads during the Super Bowl next February, the NFL said. The NFL said it expects to have another national sponsor soon.
Twitter is preparing for one of the most highly anticipated IPOs since social media platform.