Variables can be defined by the type of data (quantitative or categorical) and by the part of the experiment (independent or dependent).
In research, an independent variable is the factor you deliberately change or control, while a dependent variable is the outcome you measure. Think of it as cause and effect — the independent variable is the cause you manipulate, and the dependent variable is the effect you observe.
Variables in math are symbols, often letters, that represent different values in various situations. They help us understand and solve problems with changing values.