Wing clipping is not necessary, but some chicken keepers prefer to clip their chicken’s wings to keep them from flying over fences or up into trees. Done correctly, wing clipping is not painful for the bird. For everyone’s safety (including the chicken), it’s best to clip wings with two people: one to hold the bird and one to clip.
Watch a clip in action
This is a good video, although the chicken owners seem a little afraid of their new chickens.