Differential calculus is the study of rates of change of functions using limits and derivatives. Differentiation is the algebraic method of finding the derivative, which is the rate of change of the y-axis with respect to the x-axis or slope at a point. A limit is the value a function approaches as the input approaches some value. A function is continuous if it has no holes or jumps at any point in its domain. The tangent line touches a curve at a point but does not cross it, and the normal line is perpendicular to the tangent line. Maxima and minima refer to places where a function reaches a local maximum or minimum value. Rate refers to the speed of change of a function.