stderr stands for "standard error," which is a stream used in computing to output error messages and diagnostics from programs. It is separate from the standard output stream, allowing users to distinguish between regular output and error messages. This separation helps in debugging and logging, as errors can be redirected to different files or displayed on the screen without mixing them with normal output. In many programming environments, stderr is typically displayed in the terminal or console. By default, it is often directed to the same place as standard output, but users can redirect it to a file or another output stream for better error management.