✅ How to define and call custom functions ✅ Using different types of function arguments (positional, keyword, default, *args, **kwargs ✅ Understanding return values and variable scope ✅ Writing recursive functions and when to use them ✅ Creating lambda (anonymous) functions for short operations ✅ Using functions to keep code modular and reusable ✅ Applying functions in real-world problems like calculators, converters, and text analysis