Science is above all the study of nature. Before science was developed, humanity explained things with stories. While this was satisfying, it did not allow people to do anything much with nature. One of the first sciences was the making of tools. “If we chip these particular stones in a certain way, we can make a weapon.” This simplistic science predates Homo sapiens. Still, it was not the use of what we would call the scientific method.
Developed into its modern form by such people as Galileo and Leonardo da Vinci in the Renaissance, the scientific method begins with observation. A star is observed in the sky. Water is observed to boil. Wood catches fire and burns. The scientist will first observe and then describe what he sees in the world. These observations are written down in notebooks. An observation, such as some type of animal behavior, can make up the bulk of a scientific paper.
After observation, the scientist will usually do some thinking. He thinks of questions to ask about the observations. For instance, he may observe that some color change occurs when two chemicals are mixed. An obvious question is why does the color change? At this point the scientist will have to make an educated guess. Using all the information he has about the situation, he proposes the reasons for the observed effect.
Once a scientist has his explanation, called a hypothesis, he must devise a way to test his theory. He will design an experiment. Suppose he is Isaac Newton and his theory is that gravity causes objects to accelerate when they are dropped. He designs an experiment in which he drops a cannonball and uses a strobe light flashing ten times a second to register the cannonball on film in a camera against a background of measured lines. After doing the experiment, Newton knows how far the cannonball moves every tenth of a second and can derive the acceleration due to gravity, thus confirming his theory.
Science is about learning how things work. We use this knowledge to cause change in the world. It was observed that certain elements are necessary for crop growth. As a result of this knowledge, these fertilizers are applied to crops and increase yields, thus feeding more people. Science does not end with making hypotheses and proving them. Science is also about applying this information in the real world. Without applying the knowledge about how to increase crop yields, you are just wasting your time finding this information.
Science has changed the world in many ways. Doctors no longer bleed patients in a failed attempt to cure them. We do not sacrifice goats to make the wheat grow. People can communicate now without wasting resources on paper and postage and waiting days to get a message through. You can drive to another city instead of walking for days in bad weather. You can listen to music anywhere and watch movies in your own home. All these things and more are the result of the scientific method in use in the modern world.