The non-immigrant visa classification covers a broad range of visas used to enter the U.S.A. for work, pleasure or study. Some visas are considered “dual status” in that you may attempt to obtain permanent resident status  (a green card) while under that classification.  Most non-immigrant visas, however, require you to establish that you have a permanent residence in your home country that you have no intention of abandoning.  The duration of time you may spend in the U.S.A. can range from a few days to several years, depending on the visa classification that is involved.  In most situations, your spouse and unmarried children under the age of 21 may accompany you on a derivative visa.