What is Markdown?

Markdown is a lightweight markup language created by John Gruber in 2004. The idea is simple: write plain text using a handful of punctuation conventions, and a processor converts it to clean HTML automatically. A hash at the start of a line becomes an <h1>, double asterisks become <strong>, and a hyphen list becomes <ul>.

The original design goal was that the raw source should be readable as-is — you should not need to mentally parse HTML tags to understand what a Markdown document says.

How it works

A Markdown processor reads your plain text and outputs HTML. Here is what that looks like in practice:

# Getting Started

Write **bold** text, *italic*, or
`inline code` anywhere.

- Item one
- Item two

> A blockquote stands out.

```js
const x = 42
```

The conversion happens client-side in your browser — no server, no round trip. Try the Markdown Preview tool to see this in real time.

Core syntax at a glance

Markdown covers the most common text formatting needs with just a few characters. For the full reference, see the Markdown Cheatsheet.

Where Markdown is used

Markdown went from a simple Perl script to the default writing format across the developer world.

Markdown flavors

The original 2004 spec left many edge cases undefined, which led to dozens of incompatible implementations. CommonMark (2014) resolved this with a precise, unambiguous specification. It is now the de facto standard.

This tool uses CommonMark via the marked library. GitHub Flavored Markdown (GFM) extensions — tables, task lists, strikethrough — are supported by most tools including GitHub, VS Code, and Notion.

Markdown vs. HTML