This chapter discusses on two other big clouds: Amazon Web Services (AWS) from Amazon.com, Inc. and the Apache open source CloudStack cloud. It looks at the Amazon Web Services cloud and its service offerings, including how to use the AWS EC2 Dashboard to create a virtual machine instance, and how to secure shell (SSH) to that instance. The chapter focuses primarily on AWS service offerings and APIs. Synergy divides the cloud marketplace into the first tier, which consists of Amazon, Microsoft, IBM, and Google, and the second tier, which includes Salesforce, Rackspace, Oracle, NTT, Fujitsu, Alibaba, and HPE. Apache CloudStack is the second most widely used open source cloud, after OpenStack, although by all accounts it's pretty far behind OpenStack in market share. The AWS cloud provides a huge quantity of services. Amazon EC2 runs virtual machine instances, using various operating systems as the guest operating systems in the instances.