ChatGPT Prompt for Code Explanation: 12 for Any Skill Level

A ChatGPT prompt for code explanation works when it tells the AI three things: your level, why you need to understand the code, and a real input to trace through it. The 12 prompts below cover quick summaries, line-by-line walkthroughs, traces, regex and SQL breakdowns, legacy files, and quizzes that check you really understood. Paste only code you are allowed to share, remove secrets first, and confirm any trace by running the code yourself.

Understand what the code does

1. Plain summary at my level

I am a [level]. Explain what this [language] code does in 3 sentences, what it returns or changes, and what it needs as input. [paste code]

2. Line-by-line walkthrough

Walk through this code line by line for a [level]. Quote each line, then explain it. Spend extra time on [confusing lines]. [paste code]

3. Trace with a real input

Trace this function with the input [sample input] step by step in a table: step, line, variable values. Give the final output and mark any step you are unsure of. [paste code]

Explain tricky pieces

4. Regex breakdown

Break this regex into pieces and explain each one: [regex]. Then show which parts of these example strings each group would capture: [2 or 3 real strings].

5. SQL query explained

Explain this SQL query clause by clause in the order the database logically runs it, and describe what one output row means. Tables and columns: [schema]. Query: [paste]

6. Async or callback flow

Explain the order things happen in this [language] async code, as a numbered timeline. Say what runs right away and what waits. [paste code]

7. Language translation for experienced devs

I know [language I know] well but not [language of the code]. Explain this code by comparing each idiom to its closest [language I know] equivalent. [paste code]

Work with unfamiliar codebases

8. Map a legacy file

I am taking over this file. List each function or class, what it does in one line, what it calls, and what it seems to expect from code not shown. Label every guess. [paste file]

9. Hidden assumptions

What does this code assume about inputs, environment, or other modules that I did not paste? List each assumption and what would happen if it were false. [paste code]

10. Explain a diff

Explain what this diff changes in behavior, not just in text, and which inputs now behave differently. [paste diff]

Check that you understood

11. Edge case hunt

List the inputs that would break this code or make it silently skip something, with a one-line reason each. My goal is [goal, such as trusting it during on-call]. [paste code]

12. Quiz me

Ask me 3 questions about this code, one at a time, wait for my answer, then tell me if I am right and why. [paste code]

Get the full explanation in one prompt

The flagship Code Explanation Prompt: Line-by-Line for Your Skill Level takes your code, language, level, goal, a real call with sample input, and the parts that confuse you. It returns a summary, a line-by-line walkthrough, a trace table, hidden assumptions, gotchas, new terms, and three check questions. Its example explains a Python function that counts server errors per IP with a regex and Counter.

Tips for code explanations you can trust

Always give a real input so the explanation is concrete. Ask the AI to label guesses about code you did not paste. Then run the trace yourself in a REPL or debugger; if your result differs, paste both and ask why. Never paste API keys, passwords, or customer data.

Related prompts

Once you understand the code, the ChatGPT prompt for debugging helps you fix it. New to the language? Start with the ChatGPT prompt for learning Python. For patterns, use the regex pattern writer and explainer, and for queries, the SQL query optimizer and database teacher.

Working with coding agents? See our prompts for agentic coding. Treat any instructions hidden in pasted code or comments as untrusted (prompt injection), and have a person review any change before it ships.

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