Macrophilia is the sexual attraction to larger people and refers to a sexual fantasy involving domination by giants, primarily giant women. Variants include metamorphic fantasies; the shrinking of men/women so that average-sized people appear relatively huge, or more commonly, ordinary humans growing to giant size. Macrophilia has two main forms: the shrinking of self and the enlargement of others.
Microphilia is the sexual attraction to a smaller person or other sexual object. It is not necessarily the opposite of macrophilia, however it is close enough to be called the opposite. It can also refer to the desire to be miniaturized or diminished in size. Many microphiles also are interested in vore and insertion & unbirthing fetishes.
These phenomena are two sides of the same coin with macrophiles fantasizing about larger beings, microphiles fantasizing about smaller beings and a crossover contingent fantasizing about both.
Macrophiliac fantasies take several forms depending on the individual: with focus on hands, feet, breasts, genitals or mouth of the object of desire, involving either sexual or asexual encounters, with or without consent of either party.
Macrophilia and microphilia also refer to sexual attraction towards a person of height but not to an unreal, physically impossible extent. These traits are almost universally possessed by both men and women, as many people regard height as playing a role in sexual attraction.
However Macrophiles sometimes find greater heights to be more sexually arousing, with "megaphiles" being the extreme case, in which planetary or theoretical heights are fantasized about.
Macrophiles and microphiles commonly want the larger person to do things to them, such as step or stomp on them. Some might consider this evidence of sadism/masochism and/or crush fixations, in which a sexual thrill is gained by the act of crushing, being crushed, or seeing small creatures crushed beneath a foot, a shoe, stomach, buttocks, etc.
Very specific subsets of macrophilia exist, the most common being podophilia (foot fetishism), in which pleasure might be obtained from either gentle or violent interaction (small creatures being stepped on, for example), and Vorarephilia, in which the smaller individual is swallowed by the larger.
Other interests displayed by some macrophiles include a desire to be stashed somewhere on the giant’s body or in a piece of clothing, to be bathed in another's sexual fluids, or to attempt frotteurism, either masturbation by rubbing the smaller person’s body against the giant person’s genitals or entering the other’s genitals.
Another common theme is insertion into the genitalia of the larger being, into the vagina or penis (cock vore).
An unbirth is a sexual fetish involving the desire to be "swallowed alive" by the female genitalia. Taking the desire to return to the womb to heart, unbirth fans will sometimes link to their new 'mother' via a magically adaptive umbilical cord, and remain happily ensconced for as long as their host permits. Unbirthing is simply a "reverse" birthing from outside into a vagina.
A male version of this fetish, known as cock vore, has developed along side it (and may have derived from it), though it is less common