80/20 Rule is a very common term for different systems. I believe most of you realized that rule while running a project or maintaining the functional job. It is also true for software development. I have experienced several projects where 80% tasks were done using 20 % time and effort and 20 % tasks of the project demanded 80% time and effort. If you fail to understand the combination of your project tasks then there is a higher possibility that you may fall into trouble executing the project. To make success of the project you need to take extra care for those 20% tasks.