Resource guarding
Defending something valuable — food, a toy, a sofa, sometimes a person — against anyone who comes near it.
Also called: food guarding · guarding toys · possessive dog
Guarding is normal dog behaviour that has become a problem because it happens in a house full of people and hands. A dog that stiffens over a bowl is not staging a coup; it is worried the bowl is about to leave.
The instinct to take the item away to "show him who's boss" is precisely what escalates it, because it proves the dog right: approaching hands do take things. The work runs the other way — approaching hands reliably make the situation better, until the dog has no reason to defend anything.
Guarding of a person, and guarding in a house with small children, are the two versions that need professional eyes early rather than late.