Independent variables means it is not affect by the other variables(be it unknown or the dependent ones).
Example being the number of hours you take to travel from one place to another.
But a dependent variable's value is affected by the independent variables. So taking the earlier example, the speed you travelled at is based on the time taken and the distance of the place from the other.
So, to sum it up, an independent variable will change the value of a dependent variable, but a dependent variable cannot change the value of an independent variable, and the value of the dependent variable is determined by the value of the independent variable.
