Aldehydes and ketones can be reduced to alcohols through catalytic or chemical reduction. Catalytic reduction involves using a metal catalyst, typically Raney nickel or platinum, under hydrogen gas (H₂) conditions. Alternatively, chemical reduction involves the use of reducing agents like sodium borohydride (NaBH₄) or lithium aluminum hydride (LiAlH₄). Sodium borohydride is milder and is commonly used for aldehyde and ketone reductions, while lithium aluminum hydride is a stronger reducing agent suitable for a wider range of carbonyl reductions, including those of carboxylic acids and esters. The reactions result in the addition of hydrogen, converting the carbonyl group to an alcohol.