Crate training has long been accepted by professional trainers and veterinarians as one of the quickest and least stressful ways to mold desirable behaviors in dogs. Although many new dog guardians initially reject the idea of using a crate because they consider it cruel or unfair to the dog however, crate training takes advantage of your dog's natural instincts as a den animals. Wild dogs coyotes, wolves etc. use their den as a home, a place to sleep hide from danger and raise a family. The crate becomes your dog's den, where they can find comfort and solitude while you know they're safe and secure.

The primary use for a crate is house-training, because dogs normally do not soil their dens (in the wild this would attract predators). The crate can limit access to the rest of the house while they learn other house rules.

The crate can effectively confine your dog at times when he/she may be under foot (i.e., when you have guests, or at mealtimes), or over-excited, bothered by too much confusion or activity (such, as lots of children running around the house or to much noise for a young puppy to process).

Crating Caution

A crate is no magical solution to common canine behavior. If not used correctly, a dog can feel trapped frustrated and alone.

Never use the crate as punishment. Your puppy will come to fear it. 

Usually by 12 weeks your puppy can hold his/her bladder through the night given they have not been fed late and have not had access to water before bedtime. They will normally sleep when you sleep if trained to do so from the start. This does not mean that if you work all day that they can be crated all day as well. A dog that's crated all day will not get enough exercise or human interaction, thus becoming depressed, anxious and even destructive. You may have to hire a pet sitter/dog walker or take him/her to doggy daycare. 

I always say crate your dog until they are fully housebroken and are house trustworthy. My dogs still sleep in their kennels at night. They often go in them on their own to chew on toys or bones.

Remember, a crate may be your dogs den but just as you wouldn't spend your entire life in one room of your home, your dog shouldn't spend most of their life in their crate.