Throughout history there have been many revolutions that have occurred and changed human lives, such as the American Revolution and the Industrial Revolution. In the mid- and late-20th century a revolution occurred that dramatically changed the field of agriculture, and this revolution was known as the Green Revolution.The Green Revolution was a period when the productivity of global agriculture increased drastically as a result of new advances. During this time period, new chemical fertilizers and synthetic herbicides and pesticides were created. The chemical fertilizers made it possible to supply crops with extra nutrients and, therefore, increase yield. The newly developed synthetic herbicides and pesticides controlled weeds, deterred or kill insects, and prevented diseases, which also resulted in higher productivity.In addition to the chemical advances utilized during this time period, high-yield crops were also developed and introduced. High-yield crops are crops that are specifically designed to produce more overall yield. A method known as multiple cropping was also implemented during the Green Revolution and lead to higher productivity. Multiple cropping is when a field is used to grow two or more crops throughout the year, so that the field constantly has something growing on it. These new farming techniques and advances in agricultural technology were utilized by farmers all over the world, and when combined, intensified the results of the Green Revolution.