The document discusses changing global superpowers over time. From 1800-1918, the British Empire was the dominant global superpower, controlling 25% of the world's land area at its peak. From 1918-1945 power transitioned between countries as the US and USSR rose. From 1945-1990 it was a bi-polar world dominated by the US and USSR during the Cold War period. Since 1990, the US has been the sole superpower but others like the EU and China are increasingly powerful. The future is predicted to be multi-polar with multiple regional powers.