Roundtrip HTML editing is a unique feature of Dreamweaver that lets you move your documents between Dreamweaver and a text-based HTML editor with little or no impact on the content and structure of the document's HTML source code. Dreamweaver even maintains and renders some HTML that is technically invalid (for example, wrapping a <FONT> tag around multiple <P> tags) if such code is supported by browsers. The HTML source that Dreamweaver generates as you edit graphically, however, always will be technically valid.

The following are key features of roundtrip HTML editing in Dreamweaver:

	By default, Dreamweaver rewrites overlapping tags, closes unopened tags that aren't allowed to remain open, and removes extra closing tags when you switch back to it from the external editor or when you open an existing HTML document. If you don't want Dreamweaver to rewrite any source HTML, use the Edit > Preferences command to turn off all rewriting. See HTML preferences.
	Dreamweaver displays markers in the document window for invalid HTML that it does not support. The invalid tags are highlighted in yellow and the text within the tags appears as plain text. When you select the invalid tag, Dreamweaver describes the error and how you can correct it in the Property inspector. If you turn off HTML rewriting, Dreamweaver displays as invalid any HTML that it would have rewritten.
	Dreamweaver does not change tags that it does not recognize, because it has no criteria by which to judge them valid or invalid. If they overlap other tags, Dreamweaver may consider them invalid and mark them as erroneous. For example, the custom tag in the following would be marked erroneous: <MyNewTag><B> text </MyNewTag></B>.
	Dreamweaver lets you launch a text-based HTML editor to edit the current document. Dreamweaver is integrated with HomeSite (Windows) and BBEdit (Macintosh).