independent variable - It is a variable that stands alone and isn't changed by the other variables you are trying to measure.
for example, someone's age might be an independent variable. other factors (such as what they eat, how much they go to school, how much television they watch) aren't going to change a person's age.
dependent variable - It is something that depends on other factors.
for example, a test score could be a dependent variable because it could change depending on several factors such as how much you studied, how much sleep you got the night before you took the test, or even how hungry you were when you took it. usually when you are looking for a relationship between two things you are trying to find out what makes the dependent variable change the way it does.