Why should my dog learn the 'Stay' command?

Stay is also a foundation command used to tell the puppy to just relax in a (mainly) 'Down' position for an extended period of time. Teaching a dog to stay has many advantageous such as :

1. Specially effective when you have to answer the door and you dont want the dog rushing out.  

2. Keeps them from entering certain rooms/areas in the house that you dont want them to.

3. Helps them be by themselves at cafe's, restaurants, or any secure public place, if you have to be out of sight for a short while.

4. Can be used to calm an anxious or hyper dog down. 

5. Is the basis of other slightly advanced commands like 'Wait' and dealing with dogs having separation anxiety.