If the caret is positioned on a tag, the corresponding opening or closing tag will be highlighted in the text area. You can disable this feature, or change the tag highlight color in the XML>Xml pane of the Plugins>Plugin Options dialog box.

Plugins>XML>Go to Matching Tag moves the caret to the corresponding opening or closing tag.

Plugins>XML>Close Last Open Tag inserts a closing tag for the last opened tag.

Plugins>XML>Remove All Tags removes all tags from the current buffer, leaving only text.

Plugins>XML>Split Tag splits the current tag at the cursor, and creates a new tag at the same level. This is useful when editing HTML, DocBook or similar documents, for inserting many <p> or <para> tags. This command tries to match the current indenting style.

Plugins>XML>Characters to Entities converts special characters to entities in the current selection.

Plugins>XML>Entities to Characters converts entities to characters in the current selection.