The reader is your customer on the Web. The reader is king. A publication makes content available to a reader. The reason the Web was invented by Tim Berners Lee was to make scientific and academic content that was held on computers more readily available to interested readers. HTML is the original language of the Web.
Every website is to one degree or another a publication.
Content is published on the website by an individual or organization in the hope that people will come and read that content. Ideally, the organization has something to communicate that its competitors do not. Without structure, knowledge is just incoherent babble. Structure begins at how well a sentence is put together, how logically a document communicates a piece of information. On the Web, structure also relates to how well content is classified and how well that classification is presented in a navigation and search system, so that the reader can quickly and logically find what they are looking for.