An independent variable is a factor in an experiment that is changed or controlled to test its effects on other variables. For example, in a study examining how light exposure affects plant growth, the amount of light given to the plants is the independent variable. Researchers manipulate this variable to see how it influences the outcome, which in this case is the growth of the plants. Independent variables are crucial in scientific research because they help establish cause-and-effect relationships. By isolating and changing one variable, scientists can better understand how it impacts other factors, such as temperature or water levels, leading to more accurate conclusions.