Incidentally, the idea of working with a business plan is for one to keep focus on his set goals. Statistics has it that many businesses fail due to inadequate planning. If one doesn't know where he's heading to, any route seems to be the right one. Most people make great mistakes by jumping into business without adequate preparation and planning. A good business plan helps one maintain focus on his goals and execute the strategies that the plan assisted him in creating. Just like a road, one's business plan has to be consulted to make maintain his focus and not running business in a layman's way.
It's also important to show the business plan to the vendor or bank manager. If your business needs financing at the beginning, then you need to turn to one of these sources for financial assistance. With that in mind, you need to produce a detailed business plan that shows that your business is credible and also has potential for making money. Not only does the plan prove that you are serious about the business, it also shows that you have a sound business mind and a good grasp of what needs to be done in order to achieve good profits.