1.IaaS gives you infrastructure, PaaS gives you a development platform, and SaaS gives you ready-to-use software.
2.IaaS gives you the most control over virtual machines and operating systems.
3.SaaS – Software as a Service.
4.The Cloud Service Provider.
5.IAAS - Eg: AWS Ec2
PAAS - Eg : Google app engine
SAAS - Eg : Google docs