There are two main types of Hair Transplantation ; Follicular Unit Transplantation (FUT) and Follicular Unit Extraction (FUE). Also there is Direct Hair Implantation (DHI) which is an advanced type of FUE.
FUT is the oldest technique,in which the surgeon removes a long thin strip from the scalp (probably from the lower back of the head), then divides it into units under microscope, and implant them into the recipient area. Donor area of the scalp is sewn back together. Unfortunately , it leaves a significiant scar on that area.
FUE is the most preferred technique, in which sutureless method of hair restoration in which hair follicles are extracted from the back of head under local anaesthesia with the help of special micropunches and implanted in the bald area.
And in DHI ; creating the site and implanting the grafts are performed together. So the channel opening process in FUE method is skipped. Instead there is an implanter pen(choi) with a hollow needle withdraws the follicles , and implant on the recipient site.