A balanced composition feels right. It feels stable and aesthetically pleasing. While some of its elements might be focal points and attract your eye, no one area of the composition draws your eye so much that you can’t see the other areas.
Balancing a composition involves arranging both positive elements and negative space in such a way that no one area of the design overpowers other areas. Everything works together and fits together in a seamless whole. The individual parts contribute to their sum but don’t try to become the sum.
An unbalanced composition can lead to tension. When a design is unbalanced, the individual elements dominate the whole and the composition becomes less than the sum of its parts. In some projects, unbalanced might be right for the message you’re trying to communicate, but generally you want balanced compositions.