What was the great leap forward, and why was it disastrous?

The Great Leap Forward, intended to be a five-year effort, was halted in 1960 after three brutal years. The initiative is said to have cost an estimated 20 to 48 million lives as a result of catastrophic economic policy, compounded by adverse weather conditions including a flood that killed 2 million people and the subsequent crop failures that led to starvation. In addition to the fatalities, the Great Leap Forward had negative environmental impacts as communes were encouraged to set up "backyard" production plants for needed supplies such as steel, timber and cement. In 1960, an extensive drought further added to the country's troubles.