Sex Reassignment surgery is the surgical method by which a transgender physical appearance(especially the private parts or external sex organs) are surgically corrected to give appearance of the gender the person wants to be and have the major traits in action, reaction and self feelings.
If the transgender person wants to be female and medically found to be so possible, then the male external sex organs are surgically corrected to appear as female. Similarly the other way also.
Such surgeries are performed in India. There is a recent publicly reported and acknowledged case in Kerala of a mimicry-TV artist who underwent a sex reassignment surgery to be appearing as female.
However the SRS may not bring the full functionality of the organs of a normal gender person. The success and residual life depends on the already dominant physical and psychological attributes and may need counselling also. There may need some follow up surgeries also . While it is comparatively easy to do the SRsurgery from male to female, the opposite is more laborious and complex.