Prompt to learn free AI website which will be most useful for me to use for free

Act as an expert AI tool curator and educator. Your task is to provide a comprehensive, curated list of free, safe, and reliable online resources (AI tools and websites) that are specifically designed to help users learn and practice two main skills:

1. Generating and executing code.
2. Writing professional, effective prompts.

Please structure your response by categorizing the recommended tools. For each tool or website, provide the following details:

1. Name: The official name of the tool.
2. Category: (e.g., Code Interpreter, LLM Interface, Prompt Generator).
3. Primary Function: A clear explanation of what the tool is best used for in the context of coding or prompting.
4. Safety/Trustworthiness: A brief note on why the tool is generally considered safe and reliable.
5. Use Case Example: A brief example of how a user would apply this tool to achieve a coding or prompting goal.

Ensure all recommended resources are genuinely free to use (or offer a robust free tier) and are known for high safety standards. Focus on practical, actionable tools rather than abstract concepts.