A clicker is a small plastic device that makes a distinct 'click' sound. It's a tool for 'marking' a behavior at the exact moment it occurs.
First, we need to teach your dog that 'click' means a treat is coming. Sit with your dog, click the clicker, and immediately give them a small, high-value treat. Repeat this 10-15 times.
During this 'charging' phase, your dog doesn't need to do anything. You are just building the association: click = treat.

Wait for a moment when your dog is slightly distracted. Click. If their head whips around looking for a treat, you've successfully charged the clicker!
Now you can use the clicker to mark desired behaviors, like 'Sit' or 'Down', the instant they happen. This precise timing helps your dog learn much faster.