A guard dog is a type of dog specifically trained to protect property, people, or livestock. These dogs are often chosen for their size, strength, and protective instincts. Common breeds used as guard dogs include German Shepherds, Rottweilers, and Doberman Pinschers. They are typically trained to bark at intruders, deter threats, and, if necessary, physically confront an attacker. Guard dogs are not just aggressive; they also require proper training and socialization to ensure they can distinguish between a real threat and a harmless situation. Their presence can provide a sense of security for homeowners and businesses, making them valuable companions in safety.