Developmentalism is the idea that countries should focus on developing their economies to become more successful. It means that countries should work to improve their infrastructure, education and training, and industrialization to make their economy stronger. For example, if a country wants to become more economically successful, they could invest in better roads and other infrastructure, invest in more education and training programs for its citizens, and start factories to make products to sell to other countries. All of these things can help the country become more successful and prosperous.