Veterinarians and animal behaviorists alike suggest that your puppy be socialized from a young age to assist you & your dog live a happy life together. Socialization teaches your dog how to respond to the world healthily, without fear or violence. It can help you & your dog avoid further problems.
If you're afraid of taking your dog to the vet or the park because of its fear or aggressiveness, socialization can help both you and your dog. With an older dog that has been rescued or adopted, it's especially vital to take things slowly and patiently since they are more likely to have anxieties and taught behaviors. Both you and your dog will be happy once your dog can healthily confront his scary circumstances.