what are buffers
Definition A buffer solution is one which resists changes in pH when small quantities of an acid or an alkali are added to it. Acidic buffer solutions An acidic buffer solution is simply one which has a pH less than 7. Acidic buffer solutions are commonly made from a weak acid and one of its salts-often a sodium salt. A common example would be a mixture of ethanoic acid and sodium ethanoate in solution.
Another Answer: A buffer is an aqueous solution that has a highly stable pH. If you add acid or base to a buffered solution, its pH will not change significantly. Similarly, adding water to a buffer or allowing water to evaporate will not change the pH of a buffer.