The F-2 visa allows specific family members (the spouse and unmarried children under age 21) of an F-1 visa holder to come to the U.S. along with the student who holds the F-1 visa.
F-2 visa holders will need the school that has admitted the F-1 student to submit separate SEVIS Forms I-20 for each of them. They will also need to show evidence of their family relationship with the F-1 visa holder. The following are possible types of documents to evidence the familial relationship:
The State Department charges an application fee for F-2 (as well as F-1) visas. That fee was $160 per applicant as of early 2017, but check for any changes to that on the State Departments "Fees for Visa Services" Web page.
Although the F-1 visa holder must pay what's called a SEVIS fee (to cover record-keeping), using Form I-901, family members need not pay the SEVIS fee.
In addition to the documents proving the relationship to the F-1 visa holder, anyone applying for an F-2 visa will also need to supply:
Applicants for F-1 visas should plan to attend the visa interview along with the F-1 visa holder -- except children age 13 or under, who do not need to attend. You also have the option of waiting until the F-1 student has obtained the visa to apply for the F-2 visas, although the State Department prefers to see everyone at once. (But doing it in two steps could be cheaper and less of a hassle if for some reason the State Department refuses a visa to the F-1 applicant.)
Like the F-1 visa holder, the F-2 family members are restricted as to what activities they can engage in, once in the U.S., without violating the terms of their visa. For instance, F-2 visa holders may not accept employment in the United States. Violating the terms of the visa will automatically cancel it and risk the person being unable to succesfully apply for other U.S. visas or a green card in the future.
F-2 visa holders are allowed to enroll in elementary or secondary school (kindergarten through 12th grade), or in avocational or recreational studies. However, if they want to enroll full time in a course of study that leads to a post-secondary degree, they'll need to obtain their own F-1 visa first.