Arenediazonium salts are a group of organic compounds formed by the reaction of an aromatic amine with nitrous acid, leading to the replacement of the amine's nitrogen-hydrogen group with a nitrogen double-bonded to another nitrogen atom (N2+) that is then paired with an anion. These salts are key intermediates in the synthesis of various aromatic compounds, including dyes, through reactions such as azo coupling and Sandmeyer reactions.