Dogs are somewhat territorial in nature, so they can get aggressive and protective over things they like and enjoy. Resources for a dog can include anything, such as their bed, food bowl, chew toys, blankets, and even other humans. Unfortunately, severe resource guarding can make other pets and housemates uncomfortable.
Many dogs pick up possessive aggression when they are puppies. Evolution created dogs to eat whenever they find food, so young puppies get used to being defensive over their things as a survival mechanism.
If owners do not stop this behavior early, it can continue in their dog’s adult life. A small puppy yapping about food might seem cute, but a fully grown adult dog growling at people is not. In the worst-case scenarios, resource-guarding dogs can cause injury.