The use of balance in your home is one of the most important principles of Interior design. An unbalanced interior can be very uncomfortable. Sometimes this would be the desired effect but generally the goal is visual balance. Visual balance is done by the even distribution of visual weight throughout the home. I think the picture below is a great illustration of the principle of visual weight.
There are three sections to the principle of balance in interior design.
This is balance achieved with the use of dissimilar objects, with the same visual weight being used on opposite sides of a vertical axis. This is demonstrated in the picture below.
This is a very casual style of design and leads to an interior being more lively and less formal.
This type of balance is generally used in more traditional settings. This uses the same object on either side of a vertical axis as shown below.
This is a calm, dignified and stable style of design but can be static and unimaginative.
This is when the focal point is drawn to the center of the room. An example of this would be chairs surrounding a dining table.
Balance in home design and decor isn't just about placing like items opposite of each other, or making sure every thing has to be bought in pairs, although this is a good idea initially. Creating balance is about making sure the visual accessories in a room compliment and are visually evenly weighted to all of their counterparts.