A "formal" pool provides a neat, clean & classy look. This look is usually accomplished with some combination of the following:

• Clean, straight lines and/or geometric shapes
• Brick coping or "paving tiles" around the perimeter
• Brick or tiled decking, or stamped concrete

Use all of these features, and you get a very formal look. Combine some of these features with some features of a natural / free-form pool, and you'll create a style that is unique to you.