File handling lets PHP interact with files on the server, like reading logs, exporting data, or serving downloads.

readfile() is the simplest file function:

• It reads a file
• It immediately outputs its contents
• It returns the number of bytes read (or false on failure)

Important points:

• readfile() already outputs the file, no echo needed
• Paths should be explicit and safe
• In WordPress, always anchor paths using __DIR__

This function is best when:

• You only need to display or serve a file
• You do not need to manipulate its contents