How are reactions of diazonium salts broadly categorized, and what are the two main categories of reactions involving diazonium salts?

Reactions of diazonium salts are broadly categorized into two main types: 1) Reactions involving the replacement of the diazo group, and 2) Reactions involving the retention of the diazo group. In the first category, the diazo group is replaced by another functional group, leading to the formation of diverse organic compounds. In the second category, the diazo group is retained, and the reactions often involve the coupling of diazonium salts with other aromatic compounds to form azo dyes. These reactions play a crucial role in synthetic organic chemistry and are extensively utilized for the preparation of various organic compounds.