A well-known model to use when making strategic decisions about marketing, and specifically over strategies for achieving growth in a national and an international context. The model provides four main strategies for a business to choose between which concern products and markets: Market penetration (sell more in existing markets / market segments); Product Development (sell new products in existing markets / market segments); Market Extension (sell existing products in new markets / market segments); Diversification (sell new products in new markets). Options can actually be compared in terms of the degree of risk involved. Any option that involves the business in new markets, or new products, carries risk. An option that involves both of these (diversification) carries the greatest risk.