F1 visa is issued to international students to pursue a full-time course of study toward a specific educational objective at an academic institution or language training program in the United States. F1 visa applicants are required to have a residence abroad with no intention of abandoning the residence, intend to depart from the United States upon completion of the course of study and possess sufficient funds to support during stay and for the fees.

You may as long as you are a full-time student and even if your visa in your passport expires while you are in US, you are granted additional 60 days to prepare for departure from the US or to transfer to another school. Students are allowed to travel in and out of US during the period of their visa and your dependants can accompany you and they can remain in the US during your respective visa period.

You are allowed to work legally for 20 hours per week and due to some circumstances off campus work may be permitted after completion of your F1 visa. You can apply for this visa in your home country or you can convert it after reaching USA under any other type of visa. You decide on where in the US you would like to study and stay.

K1 visa is an immigrant visa issued to foreign national to allow entry into the United States for the purpose of marriage within 90 days and permanent relocation to United States. A solid intention to marry must be formed prior to initiation of the process. It can be obtained by any US citizen. In order to obtain a K1 visa you must be free to marry, meet income requirements and the two parties must have met at least once prior to filling the petition. Both parties must have a genuine relationship and mutual intent to marry upon arrival of fiance to the United States and the petitioner must be able to fulfill the financial support requirements.

Children are allowed to accompany their parents within six months of visa issuance under K2 visa. If they do not apply the visa they should be eligible for K2 visa after the parent gets married as long as they apply within one year of the k1 visa issuance. If you decide not to marry after obtaining of K1 visa and entry into the US then your fiance will have to leave US within 90 days or you will be deported and lose the chance to be granted the visa again.