In photography there is a term called fringing which can affect your photographs and can be distracting at times. The appropriate term for fringing is Chromatic Aberration. This results in noticeable color edge on the high contrast area (purple, green). This happens because the lens fails to bring all the wavelength of the color at the same focal plane. Lens dispersion is the reason of chromatic aberration with different colors of light travelling at different speed. Chromatic aberration also results in blurry image. This is more prominently visible at the wider aperture when the depth of field is too small. A good quality glass always focuses the lights at the same focal point.
One of the ways that you can reduce the chromatic aberration is to increase your depth of field by stopping down your aperture. This is because with a deep depth of field it becomes easier for the lens to converse the lights at the same focal point.
In a situation when you have no choice other than to use a widest possible aperture, you make sure that you use lens with aspheric element which is specifically designed to reduce chromatic aberration. These lenses are generally expensive.
The final way to reduce chromatic aberration is the help of post processing software. You can use programs like Photoshop or Lightroom. This is the most affordable way to reduce the chromatic aberration.
