<div class="htmlview paragraph">The advancements in technologies of computers, mass storage devices, positioning techniques, and digital communications links have made automation of navigational activities possible. The recent trend has been towards building navigational information systems. Two generations of these information systems are proposed. For the development of each generation a different design methodology and set of techniques are employed. Second generation systems are, however, envisioned to be enhanced versions of first generation systems, but are knowledge-based.</div>