Upon opening a Command Prompt, you will see a file path (e.g., "C:\Users\Chifundo"). This is called the prompt, and it shows what directory you're currently in. The blinking cursor at the end ...

os.path.join (folder, filename) ensures the path is correct for the system. On Windows, it uses backslashes (reports\summary.txt); on Linux and macOS it uses forward slashes (reports/summary.txt).