The heart of TiddlyWiki can be seen as an extensible representation transformation engine for text and images. Given the text of a tiddler and its associated ContentType, the engine can produce a rendering of the tiddler in a new ContentType. Furthermore, it can efficiently selectively update the rendering to track any changes in the tiddler or its dependents.
The primary use of the engine is to convert raw `text/vnd.tiddlywiki` WikiText into a `text/html` or `text/plain` representation for display. The transclusion and templating features of WikiText allow the engine to also be used to generate TiddlyWiki HTML files from raw tiddlers.
If you're interested in understanding more about the internal operation of TiddlyWiki, start by reviewing [[TiddlyWiki5 for Developers]] and then read the code -- start with the boot kernel [[$:/boot/boot.js]].
