It is outline of the business giving details of the finance, assets, staff, products or services and markets. It guides the entrepreneur, it identifies possible problems and it is also used in funding applications. The business plans sets out how to owner of a business intends to realize its objectives.
Remember the proverbial expression 'not seeing the wood for the trees'? You need to see the 'wood' first, then delve in and start examining the individual 'trees', meaning the individual items which you will be breaking down later. So a great point is to make sure that you have that overarching vision - and if you cannot find one, then maybe it is an indication that you are obsessing on a few technical aspects that do not necessarily make up a whole business as you had imagined it.
Whether it is travel, study, cooking or any other activity involving a process, planning is usually the first step. The same holds true for business. Business plans are probably more important than the business itself. For example, the plan for a house is more important than the house itself, though it is the house that people remember and not the plan. But the house wouldn't stand without the plan, would it?.
It is known to be the most crucial step in the successful running of the business because a well planned business venture carefully scans all the possible opportunities and threats, understand the demands of the market and arranges for the best possible resources which finally lead to the success of the business.