Page introduction: Source version: Markbridge 0.4.2. These docs are built from the repository and may include unreleased changes. Source page: https://markbridge.dev/introduction/ # Introduction > What Markbridge is, how it works, and where to go from here. Markbridge is a Ruby library that converts **BBCode, HTML, MediaWiki wikitext, and s9e/TextFormatter XML** into Discourse-flavored Markdown. You can convert individual documents or process a large collection. You can also inspect the parsed content and customize the output.  1. **Parse** — a format-specific parser reads your input and builds an `AST::Document`. You can review unknown tags in the result. 2. **AST** — a renderer-agnostic tree. The same shape comes out no matter which format went in. 3. **Render** — the Discourse renderer walks the tree and emits Markdown. The parse and AST stages know nothing about Discourse — “Discourse-flavored” is just what the shipped renderer produces. You could point a different renderer at the same AST. ## Four input formats, one renderer Markbridge ships four parsers that all feed the same Discourse renderer: [BBCode](/format-guides/bbcode/), [HTML](/format-guides/html/), [MediaWiki](/format-guides/mediawiki/), and [s9e/TextFormatter XML](/format-guides/textformatter/). Pick the one that matches your source — [Getting Started](/getting-started/) shows the exact method for each. ## When to use it Use Markbridge when you need to convert existing markup to Markdown, inspect structured content, or adapt output to your application. **Forum migration to Discourse** is the main use case. You can track unknown tags, handle conversion errors per post, and use custom AST nodes for references to uploads, users, and topics. The [migration guide](/migrating/overview/) explains that workflow. ## Find your way around * **[Getting Started](/getting-started/)** — install and run your first conversion. * **[Format guides](/format-guides/)** — exactly how each input maps to Markdown. * **[Customization](/customization/)** — build a reusable renderer, and add your own tags and handlers. * **[Concepts](/concepts/)** — the architecture, the AST, the parsers and renderer, and performance. * **[Migrating to Discourse](/migrating/overview/)** — the full forum-migration workflow.