Write short notes on the following: Platform-as-a-Service (PaaS)

Platform-as-a-Service (PaaS) Platform as a Service (PaaS) is a cloud computing model in which a third-party provider delivers hardware and software tools. It is defined as a set of software development tools hosted on the provider's infrastructure. Developers create applications on the provider's platform over the Internet. As a result, PaaS frees users from having to install in-house hardware and software to develop or run a new application. PaaS providers may use APIs, website portals or gateway software installed on the customer's computer. Force.com, (an outgrowth of Salesforce.com) and Google Apps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider's platform. PaaS does not typically replace a business's entire IT infrastructure. Instead, a business relies on PaaS providers for key services, such as application hosting or Java development. A PaaS provider builds and supplies a resilient and optimized environment on which users can install applications and data sets. Users can focus on creating and running applications rather than constructing and maintaining the underlying infrastructure and services. Many PaaS products are geared toward software development. These platforms offer compute and storage infrastructure, as well as text editing, version management, compiling and testing services that help developers create new software more quickly and efficiently. A PaaS product can also enable development teams to collaborate and work together, regardless of their physical location.