'The Fiancee Visas--The K-1 K-2 Visa

It usually takes about a year to get a fiancee visa from start to finish. First you have to have the petition approved (about 4 months) then you have to wait for the consulate to issue you a visa.
The fiancee visa is form I-129F

Why get a fiance visa? Because it is easy to get so long as a U.S. citizen is willing to marry you and you are outside the U.S. or legally in the U.S. but if you are legally in the U.S. it might make better sense to just get married and apply for a greencard than going the fiancee route.

Fiance visas last about 90 days and cannot be renewed. If you acquire a fiance visa you can apply for permission to work pending the wedding and receipt of a greencard. With a K-1 visa your children can get K-2 Visas and come to the United States and then apply for greencards after you get married.

What are the requirements to get a fiance visa?
1) you must have met and seen each other within the preceding 2 years of your application (unless this should be waived for religious reasons.)
2) there must be an intent to get married once you arrive in the U.S. (you have to show that there are real wedding plans in place, an engagement ring, invitations, date, place of reception, etc.)
3)the spouse must be a U.S. citizen not just a permanent resident or greencard holder.
4) both you and your spouse must be legally able to get married (no polygamy, or underage marriages allowed.)