What is the purpose of Python's built-in help function?

The purpose of Python's built-in help function is to provide documentation about Python objects and functions. When you invoke this function, it allows you to access the built-in documentation dynamically from within the interpreter. By using it, you can gain insights into various elements such as modules, classes, functions, and methods. This makes it an invaluable tool for both beginners who are learning Python and experienced programmers who need quick access to documentation while coding.

For instance, by calling help(str), you can learn more about string methods available in Python. This is particularly useful when you're looking to understand how to use certain features without having to leave your coding environment to search through documentation externally.

The other options do not accurately capture the primary function of the help system. While syntax highlighting is important for readability, it is not a feature of the help function. Returning a list of all functions in a module is more characteristic of using introspection tools like dir(). Similarly, executing Python code in an interactive shell pertains to the general functioning of the Python REPL (Read-Eval-Print Loop) rather than the specific role of the help function.