Software as a Service, or SaaS, is the delivery of a business or personal productivity solution from the Cloud to the user. It’s a software solution typically exhibiting all of the characteristics of Cloud computing (see here) with its key aspect being in the presentation of a user ready solution that can be utilised almost immediately.
SaaS solutions can usually be activated (subscription and payment usually required), on-boarded and be placed into production very quickly as no infrastructure or platform deployment is typically required. Some SaaS solutions can make use of traditional client side applications (Office 365 working with Microsoft Office is a common example) and in these situations, sophisticated deployment methods are often developed by vendors and service providers to simplify the process of local installation. It is important to note that for a SaaS application to be truly “Cloud” it is necessary for it to be able to make use of a client side application but to not require the installation.
Examples include: Office 365, SalesForce and Adobe Creative Cloud.