Everything starts with the client and ends with the client. The client has "content" to be displayed in certain ways. A photo portfolio would require different formatting than a poetry web site. Content determines layout. Content is top of the heap. Content supports the heap.
The content is passed over to the development team.
Wire frames are drawn.
An architecture is drafted.
Prototypes are built.
A testing process is established.
An agile approach is adopted. Short goals established.