Docker is cool. It is a popular technology. This small tutorial of mine,  just show how much powerfull docker is. But it is more vast than this small example.

Main or Basic Reasons :
Docker encapsulate everything an application needs to run. Thus it ease the creation, deploy and the delivery of an application.
Docker containers make things platform indepenent for any machine running docker
Docker containers has just the minimum set of operating system software needed for the application to run and  also speed up performance, decrease the storage requirements.