The welcome, friends and office refers to the tile definition names (the one to right side of the = sign). For tile views we use "org.springframework.web.servlet.view.tiles2. TilesView" class. You can also have other views together with the tile views. The about url is mapped to the about.jsp page with is a org.springframework.web.servlet.view.JstlView.
The baseLayout.jsp file contains the table structure to hold the different regions.