By John Bowman, CBCNews.ca

Yesterday, two different Amber Alerts made it to Twitter's tending topics. One was fake; one was real. Can you tell the difference?

AMBER ALERT: W States- 4 Hispanic kids ages 4-9, in 98 Mercury Sable. Nevada plates #369SDH. Kids' last name: Mata-Martinez

RT **AMBER ALERT** 3 YR OLD GIRL WAS TAKEN BY A MAN DRIVING A NEWER SILVER TRUCK IN IDAHO FALLS,ID LIC. PLATE #72B381. KEEP it goin

The first one is a real Amber Alert issued Sunday in California and Nevada. The second one is a fake alert that's been circulating in email forwards since at least February. In an earlier version of the message, the girl was said to be seven years old, not three.

As readers of Snopes.com know, nuisance Amber Alert messages fall broadly into two categories: Genuine reports that continue to circulate long after the child in question has been found, and fake alerts for children who aren't missing or don't exist.

Well-meaning folks will forward these emails and, now, retweet the details of an Amber Alert without checking if they're real or current. This diminishes the effectiveness of the Amber Alert system.

If you're tempted to spread the word about an Amber Alert, be sure to check the website of the U.S. National Center for Missing & Exploited Children, which lists all the current Amber Alerts.