A calming signal is a behavior that a dog does to calm itself or others.
Dogs often do this when they themselves are feeling anxious or stressed, or when they are about to get into a conflict with others.
This concept was first proposed by Turid Rugaas in Norway in the 1980s.
Typical calming signals to keep in mind are sniffing the ground, yawning, shaking, scratching, and licking the nose.
But actually there are many more: licking frontfoots, raising ears, bristling, raising frontfoots, clicking teeth, etc...
There are nearly 30 different types of behavior, and when a dog is doing any of these things, it means that it is feeling anxious.
If you watch your dog closely, you will notice behaviors that it doesn't usually do.
If you notice calming signals, try to think about what is stressing your dog out, or talk to your dog to ease its anxiety.