It’s a potty training tool – if introduced correctly, the crate will be seen as your dog’s “den.” Since the den is meant to be a bedroom of sorts, your dog does not want her area to be dirty. Therefore, the majority of dogs will not go to the bathroom in their crates. HOWEVER: please be mindful of the length of time your dog can hold her bladder. With puppies, good rule of thumb is how old a dog is in months is about how many hours she can hold her bladder. So a 3 month old puppy has to go potty about every 3 hours. You should NEVER leave a dog in a crate for more than 9-10 hours at a time. Every dog, no matter what breed or age, needs to get outside and get some food/water/exercise and attention from you!
It’s a house training tool – when you have a new dog in the house, there is a very good chance she does not know the rules of the house. For example, she may believe everything in the house is fair game when it comes to toys. How is she supposed to know what’s okay to chew on and what’s not? The best way to teach her is to take away whatever she is playing with that she shouldn’t be and replace it with an acceptable toy. If you are not home, you are not able to do this. Therefore, it is good to put the dog in her crate while you are gone so she cannot get into trouble. Most dogs, especially puppies, are very curious and can get themselves into trouble very quickly when unsupervised. So until your dog is completely trained, it is best to have her in her crate while you are gone so she does not harm herself.
Once your dog is completely trained, you can leave her loose in the house while you are gone.