Light on -- means there's candy. Light off -- means keep walking.

This used to be how you'd know if a family was handing out candy on Halloween. Now there's an app for that.

Many people already use the Nextdoor app, which is a private social network with the people in your neighborhood.
You can post about block parties or alert neighbors about break-ins.

To know who plans on passing out candy this Halloween, click the Treat map and click whether you plan to pass out candy.

Any house with a candy corn on it is giving out candy. Not everyone is on this site, so you can still use the light on and light off method.