Raising a canine companion is a lot like parenting a child.* Your puppy or dog needs love, socialization, education, boundaries, and benevolent leadership just as your children do. Raising a happy polite family dog relies on lots of positive reinforcement, a sense of mutual respect, clear human-canine communication and setting realistic expectations.
If you grew up with a dog, you may have seen family members hit the dog or bop it on the nose with a newspaper as a form of discipline. You might have taught a dog to sit by pushing down on its hind end. That was the norm 20 years ago. Today, we know better.
Punishment-based methods sometimes appear to offer instant results. Unfortunately, not only are those results fleeting, punishment inevitably ends in fall-out. Some methods--such as jerking the leash of your pup when it pulls toward another dog on leash--make the behavior worse in the long term. Other methods such as "scruffing" a dog when it makes a mistake damages the human-canine bond and can create anxiety in the animal or lead to aggressive behavior toward the human.
Modern dog trainers apply the science of behavior to all aspects of training. In my practice, I don't employ pain to teach a new behavior or to change an old one. I use lures, rewards, capturing, Pavlovian conditioning, desensitization and much more.
*Important caveat: this is not to say that dogs are furry humans. They are definitely not. Yet, if we can understand the similarities between raising dogs and children, we are better situated for success.