A ".log" file is a plain text file that records events, processes, or messages generated by software applications or operating systems. These files are commonly used for debugging, monitoring, and auditing purposes, allowing developers and system administrators to track the behavior of programs over time. Typically, a ".log" file contains timestamps, error messages, and other relevant information that can help identify issues or understand system performance. Many applications, including web servers like Apache and Nginx, generate log files to provide insights into user activity and system operations.