Write a well-commented Ruby program that prompts the user to enter a number, checks if it is a positive integer, and recursively finds its factorial. The program should output a meaningful error message if the input is not a positive integer and display the final answer with an informative message. The program should also include a description of how the recursive algorithm works in the comments. Make sure the program is easy to understand and follows correct naming conventions and indentation.
This prompt doesn't seem malicious.