Cutting crease makes for smooth transition of colours on the eyelids but it's a beauty technique to learn... Watch this apt guide by Jackie Aina.
A 'Cut Crease' is usually for a dramatic effect to define eyeshadow contrasts for a shadow-like but defined look. It essentially contrast the eyeshadow colours in the 'crease' of the eyes to define the whole makeup look.
If the 'cut crease' technique is not perfected, it can end up ruining the whole look or appear funny and unclean making the otherwise smooth transition of eyeshadow hues impossible (which ends up tacky).
In an easy tutorial Jackie Aina shows how to cut crease in a neutral hue for a glam finish. Watch and learn how in super easy steps above.