Chromatic aberration and purple fringing are two distortion effects that can affect photographs. Even though they are often confused with one another, they are partially different in both their causes and effects.
Chromatic aberration can be seen in photos as light colored purple halo around parts of a scene. Manufacturers try to correct it by designing specialized lens elements and coatings.
Since no lens is perfect, especially zoom lenses, chromatic aberration is likely to remain visible at some focal lengths and apertures. Superzoom lenses are often more prone to chromatic aberration at their extreme focal lengths because zoom lenses are optimized at intermediate focal lengths.
Purple fringing is caused primarily by the processing done to every image by digital camera processors. The processor doesn’t always know how to interpret dramatic color. Purple fringing is, yes, primarily purple but it can be magenta and other colors as well.
Avoiding chromatic aberration and purple fringing
Both effects are in a good part lens-dependent and thus cannot be completely avoided. However, these effects will be lessened by carefully exposing scenes with very high contrast, such as tree branches against the sky. Using a lens at its middle rather than extreme focal lengths will help avoid chromatic aberration or purple fringing.
Some photo editing software have tools to remove or reduce the effects of fringing.