The Great Depression was a global economic crisis that lasted from 1929 to 1939. It was the longest, deepest, and most widespread depression of the 20th century, affecting both developed and developing countries. The crisis began with the stock market crash of 1929, which led to a widespread panic and the collapse of banks, businesses, and industries. The Great Depression had far-reaching economic, social, and political consequences, shaping the course of history for decades to come.