Surrogacy is an arrangement in which a woman carries and delivers a child for another couple or person. This woman may be the child's genetic mother
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 (called traditional surrogacy), or she may carry the pregnancy to delivery after having an embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

, to which she has no genetic relationship whatsoever, transferred to her uterus (called gestational surrogacy). If the pregnant woman received compensation for carrying and delivering the child (besides medical and other reasonable expenses) the arrangement is called a commercial surrogacy, otherwise the arrangement is sometimes referred to as an altruistic surrogacy.

In a traditional surrogacy the child may be conceived via home artificial insemination
Artificial insemination
Artificial insemination, or AI, is the process by which sperm is placed into the reproductive tract of a female for the purpose of impregnating the female by using means other than sexual intercourse or natural insemination...

 using fresh or frozen sperm or impregnated via IUI (intrauterine insemination), or ICI (intracervical insemination) performed at a health clinic.

The social parents (that is, those that intend to raise the child) may arrange a surrogate pregnancy because of homosexuality
Homosexuality is romantic or sexual attraction or behavior between members of the same sex or gender. As a sexual orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions" primarily or exclusively to people of the same...

, female infertility
Female infertility
-Causes and factors:Causes or factors of female infertility can basically be classified regarding whether they are acquired or genetic, or strictly by location.-Acquired versus genetic:...

, or other medical issues which may make the pregnancy or delivery impossible, risky or otherwise undesirable.