1. A method for composing a user-defined web page, comprising: at a client, using a web browser executed at the client: displaying in a browser window an authoring web page, including displaying a graphical user interface of an authoring tool that is embedded in the authoring web page; receiving user instructions submitted using the displayed graphical user interface of the authoring tool; composing the user-defined web page in accordance with the received user instructions submitted using the displayed graphical user interface of the authoring tool embedded in the authoring web page, including adding individual instances of predefined structured fields to the user-defined web page at positions specified by the user in accordance with first user instructions and placing user specified content within the instances of the predefined structured fields in accordance with second user instructions distinct from the first user instructions, wherein a respective instance of the predefined structured fields in the user-defined web page corresponds to a geometric region of the user-defined web page having a visible and adjustable boundary; and in accordance with a publication instruction submitted using the displayed graphical user interface of the authoring tool embedded in the authoring web page, sending the user-defined web page to a server for online publication as a web page.