What is the purpose of an acid-base buffer and how do its components function?

19.1 What is the purpose of an acid-base buffer?
An acid-base buffer is a solution that resists significant changes in pH when small amounts of a strong acid or strong base are added. It maintains a relatively stable pH by neutralizing these additions.

19.2 How do the acid and base components of a buffer function? Why are they often a conjugate acid-base pair of a weak acid?
The weak acid component of a buffer neutralizes any added strong base, while the conjugate base component neutralizes any added strong acid. They are often a conjugate acid-base pair of a weak acid because weak acids and their conjugate bases do not fully dissociate, allowing them to absorb $\text{H}^+$ or $\text{OH}^-$ ions without causing a drastic change in the solution's pH. This ensures that both components are present in sufficient concentrations to effectively neutralize additions.