The Site Architecture is the structure of pages and the program part of the site. Architecture helps to introduce all partitions of the site visually, it's very important during development. The owner of the site can immediately see exactly what partitions are included, the designer saw what pages one needed to develop and made page-proof, the reiter knows particular partitions to be filled with contents.
To create a site without prescription of architecture is the same as constructing a building without a drawing. Before to start writing the code, one must understand what the site will consist of and how it's better to allocate information.