Alignment refers to the layout of items along invisible but easily identified lines. Alignment is important because it keeps photographs and other art items aligned on one or more sides and enables readers to view them together and increases unity. There are four types of important alignment they are; horizontal, diagonal, vertical and curved. Horizontal alignment aligns photos and other items across the page. Vertical alignment aligns items down the page, diagonal alignment aligns photos diagonally on the page. Curved alignment aligns photos.
Here is a website that contains tips for web design and alignment tips: http://www.advansys.com/blog.asp/a=147/website_design_tip_alignment
Robin Williams- Is known for her graphic design icons. She is most known for her book Non- Designer Design Book- which teaches graphic design information on a college-level graphic art course.
*The information in this post comes from Strategic Publications.