How do you implement custom Django middleware?

Custom middleware implementation:\n\n**Class-based middleware:**\n```python\nclass CustomMiddleware:\n def __init__(self, get_response):\n self.get_response = get_response\n \n def __call__(self, request):\n # Process request\n response = self.get_response(request)\n # Process response\n return response\n \n def process_view(self, request, view_func, view_args, view_kwargs):\n # Called before view\n pass\n```\n\n**Registration:**\n• Add to MIDDLEWARE setting in settings.py\n• Order matters - middleware executes in order\n\n**Use cases:**\n• Authentication\n• Logging\n• Request modification\n• Response headers