A well-defined business model should clearly articulate your function in the market, including how you make money, what inputs you depend upon, who your target customers are, and what value you are creating for them. It is a structural representation of how your business functions that concisely articulates what opportunities and challenges you will encounter with this business. If your business were a black box machine, this would be the instruction manual.

via 7 Business Model Personalities | Inc.com.