Science is the organized study of the natural world through observation and experimentation. There are four main branches of science: chemistry, physics, earth science, and life science. The scientific method is used to study science and involves identifying a problem, gathering information, forming a hypothesis, testing the hypothesis through experiments, analyzing results, and drawing a conclusion. Key parts of an experiment include a control and variables. Scientific theories are explanations of observations that can change over time with new evidence, while scientific laws are statements that are always true.