This book is composed by the result of a surveys done by master students on different areas related with the ÒExecution Environment of Distributed SystemsÓ course in the CANS master program at UPC. This book presents an overview about some technologies related with the Clouc Computing talking about different issues like Semantic Web, Cloud Computing in the Mobiles, Green IT, Distributed Filesystems, Pervasive Computing paradigm and Virtualization.