Terminological turmoil and changing dynamics of computing technology had been so rapid at its journey could be traced back from 1960 when John McCarthy predicted that someday computing would be organized as a public utility. In the early 90s, Ian Foster coined the term 'Grid computing', which talked about technologies that would make computing power available 'On demand' to consumers. This paper attempts to demystify the intricacies involved in cloud computing. Models of cloud computing and its effective implementation for mid-sized organization is emphasized. Lastly, it has been attempted to explore how cloud computing can extend Library services for better sustainability.