What Software really is and why it needed?

Software is a term for a set of instructions, which makes a computer to perform a task. The set of instructions are commonly known as a program.

When we talk about computer to give instruction we must be aware whether it can do the task and what hardware is needed to do that task.The problem arises that how we communicate with hardware.there must be interface between hardware and program.for eg. if i want to print a document there must be program to enable printer and pass the data from computer to printer.and computer must be able to access that program.