Eucalyptus stands for “Elastic Utility Computing Architecture for Linking
Your Programs to Useful Systems” and provides an open source software infrastructure to implement clusters in cloud computing platform.
It is used to build private, public and hybrid clouds. It can also produce your own datacenter into a private cloud and allow you to extend the functionality to many other organizations. Eucalyptus provides APIs to be used with the web services to cope up with the demand of resources used in the private clouds.