The most important business software ever developed must be the spreadsheet. Anybody who is old enough to remember forecasting the next years business by hand with the aid of a calculator will know the frustration of recalculation rewriting and generally spending time which removed by a spreadsheet template where calculations ripple through instead of all having to be calculated by hand.
Database systems developed through several different branches.
Report generation started with punched card counting systems, and progressed via computer systems to provide both report generators and report generator languages.
Database Filing systems developed from COBOL systems, which enabled names for both records and fields, instead of physical field definition.
Query systems generally developed from a variety of online enquiry systems.
The modern fourth-generation language or 4GL has now become very sophisticated system for design of complete business systems.
Operating software started with mainframe computers and the necessity, amongst other things, to schedule the tasks that the processor had to undergo.
The computer operators were able to adjust schedules for urgent jobs and put processing tasks in order of priority.
The development of the personal computer both from Apple and Microsoft started a different approach where scheduling was not as important as ensuring that the complex application software being developed could be best used.
The UNIX system and later Linux for microprocessors follows the conventional operating system, where schedules can be done and the security of the files set for the appropriate use and user. I am great admirer of UNIX having developed complete small systems using the 200+ UNIX commands.
Networking software developed with the need to link personal computers together. The original UNIX system used a star networking system to link users into it. (Most large computers had developed this facility previously). The development of the bus system and RS 232 interface concentrated networking on this system, which together with TCP/IP became standard.
Software such as the Android operating system is almost a standard for tablet computers, enabling a variety of applications and facilities to be available from a small touchscreen. Contrast the tablet with systems undertaking large amounts of business processing.