The document defines a trade cycle as periods of good and bad trade characterized by rising/falling prices and low/high unemployment. It lists the key features of trade cycles like periodic waves in economic activity with different phases of prosperity, recession, depression, and recovery. Various theories of trade cycles are also discussed, including endogenous theories like innovations theory and psychological theory, and exogenous theories like weather theory. The four phases of business cycles - prosperity, recession, depression, and recovery - are explained in detail. Different methods to control business cycles are also mentioned, like monetary policy, fiscal policy, and automatic stabilizers.