The serial number is the 6-digit number on the bottom of your DipJar. We've color-coded the serial numbers on your Dashboard so you know the last time your DipJar has pinged. A ping is our fancy way of knowing when your DipJar talks to our servers, which gives you an idea of your DipJar's connectivity.
Green means your DipJar pinged less than 5 minutes ago.
Yellow means your DipJar pinged within the past 30 minutes.
Grey means your DipJar pinged longer than half an hour ago.