Each type of software performs a completely different job, but all three work closely together to serve useful functions. While some special-purpose programs do not fit neatly into any of these classes, most software does.
Programs run in the memory portion of the system.
While running, programs are known as processes or jobs . The Computer System Software Relationships illustration shows the relationship between the different software programs and the hardware. Application Programs Application programs are the top software layer. You can perform specific tasks with these programs, such as using a word processor for writing, a spreadsheet for accounting, or a computer-aided design program for drawing. The other two layers, device drivers and the operating system, play important support roles.