Protective relays are critical safeguarding devices used in electrical power systems to detect faults—like overcurrent, under-voltage, or insulation failures—and automatically initiate circuit breaker tripping to isolate affected network segments. This rapid action prevents equipment damage, maintains system stability, and protects personnel. Relays are engineered with key performance characteristics—speed, sensitivity, selectivity, reliability, and security—to ensure faults are addressed precisely and swiftly. Over time, the field has shifted from electromechanical relays to advanced digital or numeric relays. These microprocessor-based units offer superior accuracy, multifaceted protection functions in a single housing, and enhanced monitoring, diagnostics, and remote communication capabilities. They play vital roles across generation, transmission, distribution, and industrial sectors, often working within layered protection zones to isolate faults while keeping healthy grid segments operational. The market is evolving rapidly due to the rise of smart grids, renewable energy integration, and cybersecurity concerns. Digital protective relays are now designed to integrate with IIoT platforms and withstand cyber threats, while delivering flexible, data-driven protection and AI-enhanced fault detection. Despite these advances, utilities face hurdles in cost-effective adoption due to infrastructure compatibility, integration complexity, and upgrading legacy systems.