Every successful business (1) creates or provides something of value that (2) other people want or need (3) at a price they're willing to pay, in a way that (4) satisfies the purchaser's needs and expectations and (5) provides the business sufficient revenue to make it worthwhile for the owners to continue operation.
The Personal MBA: A World-Class Business Education in a Single Volume (ed. Penguin UK, 2011) - ISBN: 9780141971094