Persistent Systems refers to two main entities: a global IT services company (Persistent Systems Limited) focused on digital engineering, AI, and cloud; and a defense tech company (Persistent Systems, LLC) specializing in mobile ad hoc networking (MANET) for military/first responders with their Wave Relay® technology. The IT firm offers services like software engineering, data analytics, and AI solutions, while the defense firm provides secure, reliable connectivity for difficult environments, uniting warfighters and machines on a common network.