Markdown is a lightweight, plain-text syntax for structuring prose that can be converted to HTML and many other formats. Think of it as a small DSL for documents that remain readable as plain text while rendering cleanly on the web - commonmark.org 
Markdown is a: > DSL for creating HTML documents that are still readable as plain text.
# Modern use in editors
Today, Markdown is the default writing mode in many text editors and note apps. Editors provide live preview, outline navigation, and extensions for linting and export. This means writers can stay in plain text while enjoying rich editing features.
- Visual Studio Code offers split-view preview, link validation, and workspace-wide refactors - code.visualstudio.com
- Obsidian layers linking, graph views, and plugins over Markdown files on disk - obsidian.md
- HackMD focuses on real-time collaboration and publishing - hackmd.io
- Typora and iA Writer provide minimalist, focused writing with instant formatting - typora.io
- Pandoc converts Markdown to PDF, DOCX, LaTeX, slides, and more - pandoc.org
# Practically
Markdown is a pragmatic baseline for text: - Headings, paragraphs, emphasis, links, images. - Lists and code fences. - A familiar punctuation-only syntax that round-trips well through git.
More recently markdown has become the default medium with which humans interact with ai, particularly in agentic coding scenarios - see plan.md.
This complements Markdown rather than replaces it: prose for people, semantics for programs.
# See also