Consider a big file having many lines of code. This also helps in maintenance as we have to change at one place if we make future changes to the functionality. If functionality is performed at multiple places in software, then rather than writing the same code, again and again, we create a function and call it everywhere. Functions help us in reducing code redundancy.ISRO CS Syllabus for Scientist/Engineer Exam.ISRO CS Original Papers and Official Keys.GATE CS Original Papers and Official Keys.