Briefly describe the three most common approaches to cloud computing, and compare the risk levels and potential economic benefits of each approach

IaaS provides Internet-based client access to hardware platforms on which clients' system and application software can run. PaaS provides Internet-based client access to a hardware platform with preinstalled system software on which the client installs and configures its own application software or content (for example, a hosted Web site). SaaS offers Internet-based client access to a combination of hardware, system software, and application software (for example, Google Mail).
From the client's perspective, the main risks of cloud computing, compared with using in-house resources, are vendor lock-in, security, and legal ownerships of software and data. Few cloud computing standards exist, which makes cloud vendor services generally incompatible with one another, and this incompatibility makes switching from one vendor to anothermore difficult. This difficulty is lowest with IaaS and highest with SaaS. Security is a bigger problem with cloud computing models because more potentially dangerous or sensitive information traverses public networks. When software and data are stored on a vendor's systems, legal ownership must be specified as part of the service contract.