When designing shelves of this nature, the manufacturers understand that these shelves are hanging with no external support. Therefore, they are specifically designed to be reinforced. This is done by adding attaching screws into the wall and the internal brackets are made from durable materials. They are also extended enough to give excellent support. With this type of design, you are able to put heavy items on these shelves without worry.
When you first get started on home interior decorating, it is a good idea to have at least some notion of the kind of color scheme you might like. That is not to say that you cant change your mind while you are working out a plan. It is much better to change at this stage than when you already have the paint on the walls.