But what does surrogacy involve?

Someone carries baby: A selected female will carry your embryo and deliver the baby on your behalf. Its a good tool for someone who had hysterectomy or issues with uterus and can't carry baby but can produce eggs

Clarification: If this was said i apologize, but i'd add the word 'surrogacy' is too vague. Legally and ethically there is gestational surrogacy and true surrogacy; in the former the embryo is not genetically related to the woman carrying, in the latter it is. Gestational surrogacy is legally solid in all 50 states; there are no absolute legal precedents for true surrogacy anywhere in the us.