Markdown: The Universal Language for Talking to AI

This chapter shifts to a lighter topic: something you probably use every day but might not know the name of: Markdown.

Let me start with a bold claim:

Markdown is the single most important format you should learn in the AI era.

Why? Read on.

What is Markdown?

In one sentence: Markdown is a way to write plain text with formatting controlled by symbols.

Plain text has no formatting—no headings, no bold, no lists. On the other hand, rich text formats like Word are too heavy: they require special software to open and produce large files.

Markdown is the “just right” middle ground: with a few simple symbols, you can add formatting to plain text.

For example, if you write:

# This is a heading
**This is bold**
- This is a list

It displays as a formatted heading, bold text, and a list. Simple as that.

Why You Must Learn Markdown in the AI Era

Reason 1: AI Speaks Markdown

Have you noticed that when ChatGPT, Claude, Gemini, and other AIs reply to you, they automatically include bold text, headings, lists, and code blocks?

That’s Markdown.

AI doesn’t output Word documents or PDFs. Its default output format is Markdown. Every table, bold text, and code block you see in this tutorial—all Markdown.

Not learning Markdown is like talking to someone but not understanding the words they write. Can you still communicate? Yes. But it’s far less efficient.

Reason 2: It’s Everywhere

Markdown isn’t a proprietary format for a specific piece of software; it’s a universal standard. The number of tools that support Markdown is countless:

Learn one format, use it everywhere. Notes you write in Obsidian keep their formatting when copied to GitHub. Throw them at an AI, and it understands perfectly. Try that with Word?

Reason 3: Incredibly Small Files

This might surprise you: For the same content, a Markdown file is over 20 times smaller than a Word file.

Why? A Word .docx file is essentially a compressed archive of XML files, stuffed with style definitions, font information, and document properties. Even if you write just one line, the file is tens of KB.

Markdown is plain text. The file size equals the amount of text you write. No extra baggage.

This is especially important in AI scenarios. When you send a document to an AI for analysis, Markdown consumes fewer tokens, processes faster, and costs less. All those XML tags and style definitions in a Word file get counted as tokens, wasted.

Reason 4: AI Understands Markdown Better

Many people don’t know this.

If you give an AI a Word document, it first has to convert it to text. During conversion, formatting can be lost, tables can be misaligned, and images disappear.

Give an AI a Markdown file, and it reads it directly. Markdown is plain text itself—no conversion needed, zero loss.

More importantly, Markdown symbols (headings with #, lists with -, code with ```) inherently tell the AI, “this is a heading, this is a list, this is code.” The AI can understand your content structure more accurately.

Learn Markdown in 10 Minutes

There are only about a dozen Markdown syntax elements, and even fewer are needed for daily use. Below, they are ordered by frequency of use, starting with the most common.

1. Headings

Use # followed by a space. The number of # symbols indicates the heading level:

# Heading 1 (largest)
## Heading 2
### Heading 3
#### Heading 4

For daily use, up to level 3 is enough.

2. Bold and Italic

**Bold text**
*Italic text*
***Bold and italic text***

Bold is used most often, italic occasionally.

3. Lists

Unordered lists use - or *:

- Item 1
- Item 2
- Item 3

Ordered lists use numbers followed by a period:

1. First step
2. Second step
3. Third step

Lists can be nested by adding two spaces before the sub-item:

- Main item
  - Sub-item
  - Sub-item

4. Code

Inline code uses single backticks:

Type `claude --help` to see help

Result: Type claude --help to see help

Code blocks are wrapped with three backticks, and you can specify the language:

```python
print("Hello World")
```

This is especially useful when communicating with AI. When sending code to an AI, wrap it in a code block so the AI can more accurately identify the code boundaries.

5. Links and Images

[Link text](https://example.com)
![](https://example.com/image.png)

Images are just links with a ! in front.

6. Blockquotes

Start with >:

> This is a blockquote.
> It can span multiple lines.

Result:

This is a blockquote. It can span multiple lines.

7. Tables

| Column 1 | Column 2 | Column 3 |
|----------|----------|----------|
| Content  | Content  | Content  |
| Content  | Content  | Content  |

Table syntax looks complex, but you don’t need to write it by hand. Just ask the AI to generate it for you. Say “organize this data into a table,” and the AI will output a Markdown table.

8. Horizontal Rules

Three or more - on a single line:

---

Used to separate different sections of an article.

9. Strikethrough

~~Deleted text~~

Result: Deleted text

That’s Enough, Really

The 9 syntax elements above cover 99% of daily use cases.

You don’t need to master Markdown. Headings, bold, lists, and code blocks—master these four and you can handle most situations. Look up the rest when needed.

And Markdown has one advantage: It’s okay if you can’t remember it all now; you’ll learn it by using it. AI outputs Markdown, so as you read AI responses every day, you’ll naturally become familiar with these symbols.

How to Use Markdown to Improve Communication with AI

After learning Markdown, here are a few tips to make your conversations with AI more effective:

Tip 1: Use headings to structure your input

# Background
I’m working on a blog project...

# Requirements
Help me implement the following:
1. Article list page
2. Article detail page

# Constraints
- Use Hugo framework
- No database needed

Much better than a big block of text. With headings, the AI can more accurately understand the structure of your request.

Tip 2: Wrap code in code blocks

Don’t just paste code directly; wrap it in a code block:

Help me check what’s wrong with this code:

```python
def hello()
    print("hello")
```

The AI can precisely distinguish between your words and the code.

Tip 3: Use lists to enumerate requirements

Write an article for me with the following requirements:
- Around 1000 words
- Conversational style
- Divided into three sections
- Each section has a subheading

Much clearer than “Write me an article around 1000 words conversational style divided into three sections each with a subheading.”

Where to Practice?

You don’t need to find a specific place to practice. If you’re using Claude Code or Codex as you follow this tutorial, you’re using Markdown every day—you just didn’t know its name.

If you want a dedicated place to write Markdown, here are a few recommendations:

Beginners are recommended to use Obsidian. It’s free, easy to use, and works well with AI. If you want to dive deeper, check out the author’s other book, “Obsidian Handbook.”

Summary

What you learned today:

1. What Markdown is: A way to write plain text with formatting controlled by symbols, over 20 times lighter than Word
2. Why learn it in the AI era: AI outputs Markdown, it’s everywhere, files are small, AI understands it better
3. Core syntax (4 are enough): Headings #, bold **, lists -, code blocks ```
4. Complete syntax (9 cover 99%): Plus links, images, blockquotes, tables, horizontal rules
5. Tips for communicating with AI: Use headings to structure, wrap code in code blocks, use lists for requirements

Key takeaways:

• Markdown is the “native language” of AI; learning it means learning to communicate efficiently with AI
• Learn the basics in 10 minutes, look up the rest when needed
• No need to practice deliberately; you’ll pick it up naturally while using AI

Part 2: API and Tokens: The Technical Core