Decades of advances in computer architecture, software-intensive applications and system integration have created significant challenges for embedded systems designers and test engineers. Intrusive software instrumentation and breakpoint-based debugging are often viewed as the primary options for observing operational system internals. This narrow sight creates complicated test flows and convoluted debugging procedures. Modern embedded computing systems offer Embedded Trace as the technological answer to the encountered observability conundrum. Although an integral part of virtually all modern processors, it is frequently overlooked. Its technical foundations are little known to application engineers, test engineers, and project managers. This article explains Embedded Trace as an essential technology in the testing and debugging toolbox. It highlights its capabilities, limitations and opportunities.