A total derivative accounts for every dependence of a quantity on the variable of differentiation. Its integral contributes only boundary terms.
The total derivative is a concept from calculus that extends the idea of a derivative to functions of multiple variables. It takes into account how a function changes as all of its input variables change simultaneously.
The total derivative of a function assigns for every point of the domain a linear map with same domain, which is the best linear approximation to the function value around this point, i.e. the tangent plane.
New to topics? Read the docs here!