rir Oct 21, 2009:

Transactional sexual relationships are sexual relationships where the giving of gifts or services is an important factor. Transactional sex relationships are distinct from other kinds of prostitution, in that the transactional sex provides only a portion of the income of the person providing the sex. Those offering sex may or may not feel affection for their patrons.

In the western world, transactional sex usually involves a woman living in extreme poverty. If unable to pay her rent one month, she might have sex with her landlord. Any number of other services, legal and illegal, can be paid for with sex acts.