Platform as a service.
One of the major constraints to application development has been the availability of infrastructure on which to develop the software. Application development being a costlyu exercise in part because infrastructure capital cost had to be factored in. Platform as a service solves this by providing a cloud based platform which removes the complexity and up front cost of deploying infrastructure before the development can even begin.
So the top ones are AWS, Salesforce, IBM Bluemix, Microsoft Windows Azure, Openstack and Google APP Engine
Accenture and Oracle – Accenture and Oracle struck a deal on PAAS this year
Like many technologies, PAAS rapidly took on the qualities of an ecosystem of its own.
Mobile Paas was a major theme of 2014 as developers sought cloud based platforms to develop and run mobile apps.