Book excerpt: What's the secret to a company's continued growth and prosperity? Internationally known marketing expert Al Ries has the answer: focus. His commonsense approach to business management is founded on the premise that long-lasting success depends on focusing on core products and eschewing the temptation to diversify into unrelated enterprises. Using real-world examples, Ries shows that in industry after industry, it is the companies that resist diversification, and focus instead on owning a category in consumers' minds, that dominate their markets. He offers solid guidance on how to get focused and how to stay focused, laying out a workable blueprint for any company's evolution that will increase market share and shareholder value while ensuring future success.