Potential investors will make judgements about your business based on the business plan that you produce.
It can also help to convince customers, suppliers and potential employees to support you.
It needs to be concise and clear and answer all the key questions an investor might have. No business gets funding based entirely on their business plan but it forms the basis of all on-going discussions you might have with investors who show interest.
Download free business plan templates and find help and advice on how to write your business plan at this link.
Further information on writing a business plan is available at The Prince's Trust.