stderr is one of three standard streams—stdin, where your program reads the input data with the console; stdout, where the program sends the output data; and stderr, which has the special purpose of showing errors or other information about working with the application. Loggers often use stderr to avoid affecting the output data. For example, let’s say that you have a tool that decodes an input stream. You want the tool to send the decoded data only to the output stream. How will the program inform you about any issues it is experiencing? In this case, we can use the stderr stream, which works as an output stream, but doesn’t pollute stdout? There is stderr stream that works as output stream, but doesn’t pollute stdout