A merger is a situation when your subject's focus is being distracted or interfered with by an object in the background and two or more objects or tones come together and become in a photograph either a blob, a nuisance, or near miss. A few examples is when there is a pole or something that appears to be going through your subject. Mergers should often be avoided to keep the focus on your subject. Center weighting is when the subject is placed directly in the middle of the picture, disobaying the rule of thirds. Mergers and Center Weighting are things you would often want to avoid to keep your pictures interesting, But sometimes they can be fun.