Sofa surfing. It's when you're flipping through the channels just seeing what's on. And what's on depends on which signals are beamed from the stations to the towers and into your living room.
And month to month, that could change. If you're using an antenna you need to rescan and often! Many stations will have either changed or will be changing frequencies.
The changes started April of 2017 and don't end until July of 2020. You'll want to rescan every couple of months to have the most channel options.
Check out the reception map from the Federal Communications Commission.
When you type in your zip code, it lists all the stations you can pick up with an antenna and their strength. Also, if they're going to be changing frequencies, there will be an R on the last column. When you click on the station, like WFMY, it gives you the time frame of the change. For example, WFMY News 2, the change is March of 2020 to May of 2020.