Aldehyde is an organic compound. Its structure includes a carbon atom that shares a double bond with an oxygen atom, and a single bond with hydrogen (and a single bond with another atom or group of atoms). This makes it part of the carbonyl group. They often have a good smell to them as they are derived from different types of alcohols. As polymers aldehydes become plastics that are used in cooking, laminate countertops (Formica), or as perfume additives.