Igor Ansoff (1918–2002) was a Russian-American applied mathematician and business manager. He is known globally as the "Father of Strategic Management." Before Ansoff, business planning was largely budgeting and forecasting. Ansoff introduced the concept of —making decisions today based on future scenarios.

If you cannot find the PDF, read Ansoff’s definitive article in the Harvard Business Review (1965, republished 1987): "Strategies for Diversification." It condenses the matrix and gap analysis into 10 pages—the perfect appetizer before the main course of the full Corporate Strategy text.

In his book Corporate Strategy , Ansoff outlines a process for choosing which of the four strategies to use. This is called .

: Focuses on increasing sales of existing products in existing markets. This is generally the lowest-risk approach.

Buy a used physical copy of the 1965 original (it’s a timeless desk reference) or purchase the 2018 Penguin ebook for searchability. Then, pair it with a modern summary guide to navigate Ansoff’s dense, engineering-style prose.

The idea that management must adapt its aggressiveness and responsiveness based on how fast its environment is changing.