Common names of aldehydes are derived by suffixing 'aldehyde' to the common parent names of corresponding carboxylic acids. For instance, acetaldehyde derives its name from acetic acid, and benzaldehyde acquires its name from benzoic acid. Common names of aliphatic ketones include the names of the two flanking groups arranged in alphabetical order, followed by the suffix 'ketone'. Some aromatic ketones are named 'phenones' such that the word phenone is prefixed by the name of the acyl group. Depending on the identity of the 'R' in the acyl group, different ketones acquire different common names. For example, an aromatic ketone with methyl as the 'R' group is called acetophenone, whereas a benzene ring as the 'R' group gives the name benzophenone. In aldehydes and ketones, the locants in the common names are represented by Greek letters starting from the carbon atom adjacent to the carbonyl carbon. The hydrogen atoms linked to these carbons are also indicated with the same greek letters.