The following are general definitions for the K-1/K-2 visa. Aside from meeting these general definitions, there is also documentation that must be submitted by the U.S. citizen as well as the alien fiancé/fiancée and child/children of the alien fiancé/fiancée to establish that the relationship exists.
According to the definition provided by USCIS, a fiancé/fiancée is someone “engaged or contracted to be married”. In order for an alien fiancé/fiancée to marry a U.S. citizen, marriage must be legally possible according to state specific laws.
Moreover, to avoid a "mail-in-bride" issue or fraud, the two people must have met within the past two years. There are of course, some exceptions to this. One such example is that in some cultures, a man and a woman are not supposed to meet before marriage.
There are other instances when USCIS will classify someone as a fiancé/fiancée even though they have already married. In this case, the American citizen and his/her spouse must not have met in person, nor consummated the marriage.
To see more information on these two exceptions, please refer to the section on special K-1/K-2 visa scenarios.
(Updated 10/12/2012 by AD)
For more information on how to obtain a K-visa, please click on the following links: