How does the Henderson-Hasselbalch equation apply to buffering solutions?

The equation quantifies the relationship between pH and the ratio of conjugate base to weak acid in a buffer solution. It demonstrates that when [A⁻] = [HA], the pH equals the pKa, indicating optimal buffering capacity. Deviations from this ratio show how the buffer responds to the addition of acids or bases, thus illustrating its effectiveness in maintaining pH stability.