If you're writinging a business plan, you need to be familiar with the Business Model Canvas developed by Alexander Osterwalder. The Business Model Canvas is a strategic tool for analyzing the purpose, customers, revenue streams and outputs for a business. It can be used to develop a business model a new business, or it can be used to describe an existing business.
The advantage of the Business Model Canvas is that it is flexible, easy to implement, and provides a clear picture of the challenges for both new and existing businesses. There is a link to the Business Model Canvas below and that page is also available in Canvas. You can do to google search, or search an article index for more information.