Page layout
A grid is a set of guidelines. These can be seen by the designer, but are invisible to the end-user. Their function is to align and repeatelements on a page. A page layout may or may not stay within those guidelines, depending on how much repetition or variety the design style in the series calls for. Grids are meant to be flexible. Using a grid to lay out elements on the page may require just as much or more graphic design skill than that which was required to design the grid.