"Beware of Dog" is a warning sign often placed in yards or on fences to alert visitors about the presence of a dog that may be aggressive or protective. This sign serves to inform people that they should approach with caution, as the dog may bark, growl, or even bite if they feel threatened. These signs are commonly used by pet owners to prevent unexpected encounters and to protect both their pets and visitors. The presence of a dog can vary widely in temperament, so the sign helps set expectations for anyone entering the property.