Advanced Distribution Management Systems are one of the first mature successful products from the information age. Over a 30-year period, a series of computer applications, all related to the real-time control of electricity distribution networks, were developed to meet the challenges of privatisation, deregulation and CO2 reduction. These have evolved into ADMS, which now plays a major role in adapting traditional electricity distribution networks to meet the challenges presented by the transition to renewable generation and reducing our carbon footprint. The purpose of ADMS is explained and component functions of ADMS are described. The ADMS relationship with other corporate IT investments is also discussed. Furthermore, the maintenance needs of ADMS are described and direction is given on how to extract maximum value from an ADMS investment.