In Math, independent variables are those values that determine the value of other variables.

A variable, which manipulated or controlled by human being or the experimenter is known as *independent* variable. It stands alone and isn't changed by the other variable(which we are trying to calculate). This is also called " factors".

This type of variable manipulated by the experimenter in an experiment. So we can say that,

independent variables are variables that are systematically controlled
by any researcher to determine the variable’s overall effect on the
final outcome or the dependent variable.

For example, someone's weight might be an
independent variable. Other factors (such as what they eat, how much
they eat, how is the food) aren't going to
change a person's weight. In fact, when we are looking for some kind of
relationship between variables we are trying to see if the independent
variable causes some kind of change in the other variables, or dependent
variable.

There are three ways to manipulate independent variables: presence or
absence technique, amount technique and type technique.

In presence or
absence technique, the independent variable can be manipulated by
presenting a condition or treatment to one group of individuals and
withholding the condition or treatment from another group of
individuals.

In amount technique, the independent variable can be
manipulated by varying the amount of a condition or variable such as the
amount of a drug which is given to children within a learning disorder.

In type technique, the independent variable is to vary the type of the
condition or treatment administered.