16. The method of claim 15 , wherein: the electronic document is a markup language document; and the first portion and the second portion are nodes within a document object model (DOM) tree of the markup language document or a sub-tree comprising a parent node and one or more child nodes within the DOM tree of the markup language document.
17. The method of claim 16 , further comprising removing the first portion from the electronic document when the first portion comprises: content invisible during rendering of the markup language document; advertisements; or a reference to comment providers.