Variables are factors in an experiment that can change. There are three types of variables in a scientific experiment: independent, dependent and controlled variables. The scientist changes the independent variable in a systematic manner and measures the effects of this change on the dependent variable. The other variables are called controlled variables because the experiment is designed to keep them at an unchanging value, known as "controlling" a variable. A valid experiment should have only one independent variable.
A variable is anything that can change or be changed. In other words, it is any factor that can be manipulated, controlled for, or measured in an experiment.
There are three main variables: independent variable, dependent variable and controlled variables.
A relationship between two variables whereby a change in one coincides with a change in the other is referred to as causality.
