Four Components of a Business Model

1. What compelling reason exists for people to give you money? (or votes or donations)
2. How do you acquire what you're selling for less than it costs to sell it?
3. What structural insulation do you have from relentless commoditization and a price war?
4. How will strangers find out about the business and decide to become customers?

via Seth Godin.

Seth describes the four elements a business model needs to address. Number 1 is the value proposition; two is your financials (revenues-cost) and revenue model; three is your infrastructure management, partner network, innovation mechanisms, brand loyalty (is that structure though?); four is your customer interface and marketing efforts.

It's a break down in plain English of what other have called the Nine Business Model Building Blocks:

(via Osterwalder, Pigneur, Tucci; Clarifying Business Models: Origins, Present and Future of the Concept)