There is no doubt that undercut has regained its reign these days. What makes this cut so popular is that it is a unisex style in which the sides and the back are left short, which leaves the hair on the top long.
If the hair on the back and the sides is shaved right to the scalp, which eventually leaves the top section long, it is then known as the undershave.
Within the general classification of hairstyles and haircuts for men, for sure, the undercut is a flexible cut which can be easily modified in a great number of ways. Here are some of the variations of this unisex cut.
The undershave hairstyle is an undercut which appears as a more extreme type in which the back and the sides of the head are simply shorn down right to the scalp.
That will leave the hair long on the top. Due to the stark difference which is generated by this haircut, undershaves are regarded popular in goth and punk subcultures.
They are also worn by metalheads and skaters that grow their hair on the top past shoulder length and then tie it back. That will leave the back and side entirely shaved.
There are of course some variations on this haircut. As you see on the fashion magazine cover, there are lots of style which feature razored line.
You can apply the razor line right at the area where you make the part. Or, if you want to look much bolder, then you can have it right on the sides, lining from the area around the ears to the back.