Buffett's philosophy is elegantly simple, though maddeningly difficult to execute. He is a value investor in the deepest sense: he looks for wonderful businesses at fair prices and holds them for as long as possible, often decades. He has called this philosophy "business investing" — not stock trading.
The foundation of his thinking comes from his mentor, Benjamin Graham, who taught him the concept of intrinsic value — the idea that every business has a true worth that the market may temporarily mis-price. Buffett's gift was marrying Graham's value principles with Charlie Munger's insistence on buying *quality* businesses, not just cheap ones.
His "circle of competence" principle is deceptively powerful: know what you understand, invest only within that circle, and relentlessly resist the temptation to stray outside it. For decades, Buffett avoided technology stocks — not because he thought tech was bad, but because he could not reliably predict which companies would dominate a decade hence.
On market downturns, Buffett is almost cheerfully contrarian. He wrote in 2008, as the financial world burned: "I've been buying American stocks." While others saw destruction, Buffett saw a once-in-a-generation sale. His famous dictum — "be fearful when others are greedy, and greedy when others are fearful" — is not a sound bite but a way of life.
Buffett's concept of the "economic moat" — competitive advantages that protect a business from rivals the way a moat protects a castle — has become perhaps the most influential idea in modern investing. Moats can be brand power (Coca-Cola), network effects (American Express), switching costs (insurance), or cost advantages.
He is also famous for his patience. "The stock market is a device for transferring money from the impatient to the patient," he has said. When asked about his best investment moves, he often points not to his buys, but to his decision NOT to sell.