It's a way to communicate in an emergency, even with a loss of electricity or cellphone service.
Local amateur radio operators spent the day practicing their ham radio skills in Holmen as part of the nationwide Field Day.
The challenge is to contact as many other radio operators as you can around the country and even around the world in just 24 hours.
Radio operators said it's important people know how to use the radios, because it can be one of the only ways to communicate in an emergency.
"This is more reliable. For example, Boston when the bombs went off, cellphones went down because too many people were using them. The only reliable communication at that time was amateur radio," said Riverland Amateur Radio Club President Greg Miller.
Miller said the club also works with the National Weather Service during severe weather.
Operators will go to different places in the field and report what they see through their radios.