An Application is a piece of software that is used by Teams to carry out Functions. In this context an Application means something that is deployed on or dependent in some way on datacentre infrastructure. So Adobe Acrobat is generally not modelled as an Application but SAP would be.
Examples of Applications include:
Applications are "implemented" as Implementations. SharePoint (application) is distinct from SharePoint Online (implementation).
In cloudstep the Application is considered the "unit of measure". It means that when we are considering our strategy moving forward for ICT we are thinking about applications. There may be dozens of servers used to deliver an application but we are interested in the fate of the app itself.
For instance lets say we have SharePoint on-premises using a SharePoint 2013 farm. This farm involves several application, frontend and database servers. A logical way forward is to use SharePoint Online instead of SharePoint on-premises. When we build a plan to migrate the Application we tell cloudstep what to do with it and it works out what to do with the servers.
In the same way that we can migrate applications we can also compare different scenarios for their deployment. So we might compare the running costs of SharePoint on-premises against using SharePoint Online. cloudstep can show the total cost of ownership over time, comparing different ownership strategies along the way.