Dogs are curious and friendly, but they don't understand human social cues. If you reach out to pet a dog, they might be confused or scared by the gesture and react defensively. Your hand may seem like it's coming in for a quick pat, but the dog might perceive it as an attack and snap at you. It may be tempting to go for a high-five or a fist bump, but doing so could cause the dog to think that you are going to hit it. Plus, if it’s not used to being touched in this way, it might bite you!
Instead, try crouching down and offering your hand palm up. If the dog is feeling friendly, it will likely sniff or lick your hand in return. You can even say something like “hello” in a cheerful tone while you do this!
Remember: when introducing yourself to a new dog, it's always best to let them make the first move!