Function Definition and Call: How to Create Your First Function in Python?

Functions are a core tool for code reuse in Python, designed to solve the problem of repetitive code. By "packaging" functional modules, they save time and ensure consistency. The definition syntax uses the `def` keyword, including the function name, parameters (to receive external data), an indented function body, and `return` (to return a result, defaulting to `None`). When calling, parameters must be passed (either positional or keyword arguments), and the return value should be received. Key points to note include indentation requirements, parameter quantity matching, and unique function names. Mastering the basics of functions (parameters, return values) is crucial for advanced usage, as they allow breaking down complex logic and improving code simplicity and maintainability.