Application software consists of programs that perform a service or a function. Some application programs are general purpose. Other application programs provide specific functions.1. Horizontal-market application software provides capabilities common across all organizations and industries. Word processors, graphics programs, spreadsheets, and presentation programs are all horizontal-market application software. Examples of such software are Microsoft Word, Excel, and PowerPoint.2. Vertical-market application software serves the needs of a specific industry. Examples of such programs are those used by dental offices to schedule appointments and bill patients. Vertical applications usually can be altered or customized.3. One-of-a-kind application software is developed for a specific, unique need. The IRS develops such software, for example, because it has needs that no other organization has.