What is buffer capacity?

Buffer capacity quantifies the ability of a solution to resist changes in pH by either absorbing or desorbing H+ and OH-  ions.  More specifically, buffer capacity is the amount of either a strong base or acid that can be absorbed by the solution before the pH changes significantly. When an acid or base is added to a buffer solution, the effect on pH change can either be large or small and depends on the initial pH and the capacity of the buffer to resist the change. It is important to note that a higher buffer concentration has a greater buffer capacity.