The Application Layer

Some attempt to classify applications is made here:

http://en.wikipedia.org/wiki/Application_software

Here are a few examples:

Productivity Software

Specializing the operating system's virtual office metaphor, productivity software often attempts to virtualize the office/studio of a writer, accountant, or artist. Here are a few examples:

word processors, spreadsheets, presentation software, diagram editors, drawing/painting

Enterprise Applications

Enterprise applications are characterized by the idea that workers (and sometimes customers) of a large enterprise need to share information and business logic, but that each worker may need to have this information and logic presented in a different way.

Here are a few examples:

Databases

Business workflow systems

Project management, security, human resources, ...

Entertainment Software

How would you classify computer games?

Educational Software

Media Development Software

Image, video, sound editing

Product Development Software

CAD/CAM

Web development

Flash, Dreamweaver, ...

Software Development Software

debuggers, compilers, editors, bug reporting systems, version control systems,

Simulation Software

social, scientific, military, games

Etc.

Lots has been left out. What about social networking? Email? IM?