The ETL (Event Trace Log) file format is a proprietary binary format developed by Microsoft, primarily used by the Event Tracing for Windows (ETW) framework. ETW is a high-performance, low-overhead tracing facility built into the Windows kernel that allows developers and system administrators to log events from both user-mode applications and kernel-mode drivers. ETL files contain detailed diagnostic information, including system performance data, hardware interrupts, process activity, and application-specific events. Because these files are binary-encoded for efficiency, they are not human-readable in a standard text editor. Instead, they require specialized analysis tools to parse the event metadata and translate the binary data into a readable format. These files are essential for debugging complex system issues, analyzing application performance bottlenecks, and performing deep-dive security auditing on Windows operating systems. They are frequently generated by tools like Performance Monitor, Windows Performance Toolkit, and various command-line utilities such as logman.exe.