You maintain your own infrastructure but it consists of virtual machines hosted in your behalf. So buying new computers is as simple as a few clicks and your capital costs for maintaining computers and networks goes way down or even goes away.
You take advantage of a pre-built development and deployment environment and control the software you put out with no computers to manage. You develop and release your own software. Take advantage of powerful services available for technologies like databases, analytics, machine learning, and artificial intelligence.
You can also take advantage of applications already running in the cloud, such as email, collaboration software, document management, and web site technologies that users can use themselves without programmers or IT skills.