A: Essentially, "nonimmigrant" means "temporary" - a visa that allows a foreign national to be present in the U.S. for a limited period of time for a specific purposes, and normally to travel out of and reenter the U.S. during that period to resume that purpose. It may also carry other privileges, like the ability to work or attend school in the U.S., but not all do. Most start with a letter, a dash, and an number ("F-1," H-1B." "L-1A," "P-2") while a few have only a letter ("I"). The right to be present in the U.S. for a limited period of time is the only thing that is common to all nonimmigrant visas.
A: Yes - there are different nonimmigrant visas for different purposes. Some permit employment of different types (though normally only for one specific employer), while some permit only some other type of activity or groups of activities (going to school, getting married, providing religious guidance, etc.)
A: Almost all nonimmigrant visas have a "derivative" status (F-2 for F-1, H-4 for H-1B, etc.) that permit spouses and children under the age of 21 to accompany the principal applicant to the U.S. In most cases, spouses and family will not be permitted to do the same things that the principal visa permits the principal applicant to do, though children can attend school and spouses in certain derivative visa classes can obtain employment authorization. Where a spouse can't get employment authorization but wishes to work, they would need their own principal visa.
A: As the term "permanent" implies, Permanent Residence has no expiration date and can be lost only through abandonment or commission of certain acts. This is unlike a nonimmigrant visa which is valid only for a limited amount of time and normally has a definite expiration date. Permanent Residence can be used for any purpose - to work, vacation, go to school, or do virtually anything legal. A nonimmigrant visa can generally only be used for one specific purpose, although again there are a few exceptions.
A: This depends on the type of visa for which the person is applying. Some visas, like the H-1B and the L-1A & L-1B for instance, require a petition to be filed with U.S. Citizenship and Immigration Services in the United States. Normally, the types of visas which require a prior USCIS petition also require an employer or other sponsoring organization to petition on behalf of the foreign national. Although overseas, the foreign national in many cases will need to have secured a job offer from a U.S. employer. USCIS has regional Service Centers which handle nonimmigrant visa petitions and applications for different portions of the country and different types of cases. Immigration forms - along with certain other evidence and processing fees - are filed with the appropriate USCIS Service Center to get the visa. Often, petition or application packages are sent to a designated post office box for initial intake and data entry before being forwarded to the USCIS Service Center. As with any application, USCIS may approve, deny, or ask for more information. If the case is approved, notice of the approval will be sent through an office of the U.S. Department of State to the Embassy or Consulate indicated on the forms submitted to USCIS (these days, this is handled electronically through the "Petition Information Management System" or "PIMS" - of course, notice is also sent to the petitioning entity - company, organization, the individual in some cases, etc. - and to any attorney working on the case). The foreign national may then apply at the consulate for the visa stamp. The visa stamp is then used to enter the U.S. Some visas, such as the B-1/B-2 visitors' visas, require no prior USCIS application process and only an application at the U.S. embassy or consulate abroad. An application is made directly to the consulate, and the foreign national applicant is interviewed, normally resulting in an on-the-spot notification of approval or denial and return of the passport with the visa stamp within a short period. Even some employment-permitting visas such as the E-1/E-2 treaty Trader/Treaty Investor visas, the E-3 Australian Specialty Occupation Worker, and the TN "Trade Nafta" visa, are applied for in this manner. Finally, some nonimmigrant visas (such as the F-1 student visa and the J-1 exchange visitor visa) are a hybrid of these two types in terms of application process. No prior application through U.S. Citizenship and Immigration Services is required, but before a foreign national can apply at a consulate abroad for a visa stamp they first must obtain a form with details of the educational or exchange program from an agency authorized by USCIS to issue such a form (an I-20 form for a student visa, a DS-2019 for a J-1 visa).
A: USCIS approval determines that you (and your purpose for coming to the U.S.) qualify for the nonimmigrant status requested, and that you are authorized to be present in the U.S. in that status. The embassy or consulate determines whether anything - independent of the criteria for the nonimmigrant visa - prevents you from entering the U.S. In other words, the embassy or consulate determines whether any ground for exclusion applies. The visa stamp in the passport can be viewed as a pass or ticket to enter the U.S., while the USCIS Service Center approval grants permission to be present in the U.S. in a specific nonimmigrant status. There are exceptions to this process in the visitor context, such as the B-1/B-2 visitor visas where all that is required is the intent to visit the U.S. for only a brief period for specific allowable purposes (determined entirely by the embassy or consulate without USCIS Service Center participation), and the related Visa Waiver Program visas for visitor admission of individuals from certain specific countries (determined by the inspecting officer upon entrance without USCIS Service Center or embassy/consulate participation). Further, L-1 Blanket petitions for international transferees and E visas (E-1 Treaty Trader, E-2 Treaty Investor, and E-3 Australian Specialty Occupation) are, like the B-1/B-2, determined entirely by the embassy or consulate.
A: A foreign national who has maintained valid nonimmigrant status here and does not want to leave the U.S. and reenter will need to change their nonimmigrant status to one which permits them to do what it is they wish to do. The process of changing nonimmigrant status requires the filing of a petition or application (depending upon the type of visa sought) with U.S. Citizenship and Immigration Services. Changing status without leaving the U.S. is only possible where the foreign national has maintained valid nonimmigrant status - in other words, has not violated the terms of the nonimmigrant visa on which they are already here by staying past the expiration date, accepting unauthorized employment, etc. An individual who has not maintained status must leave the U.S. and apply for the nonimmigrant visa stamp at a U.S. embassy or consulate in their home country (after first obtaining USCIS approval of the necessary form, if the nonimmigrant visa sought requires it). This may present problems depending on whether the foreign national has built up a certain amount of "unlawful presence" time while being out of status.
A: No. If a foreign national have been granted a change of status while in the U.S., you are here legally in the new status and may do anything the new status allows (work legally, for example) from the start date of that petition. You only need to get the visa stamp the next time you travel out of the U.S. after approval, in order to allow you to reenter.
A: Only on some nonimmigrant visas. Generally speaking, asking for a nonimmigrant visa means expressing "nonimmigrant intent" - the intent to remain in the U.S. only temporarily. This is clearly inconsistent with the intent to remain in the U.S. permanently; it would therefore seem that the answer should be "no." However, certain nonimmigrant visas allow for "dual intent" - the intent to be here in a temporary nonimmigrant status for now while simultaneously wishing to obtain permanent residence eventually to remain in the U.S. indefinitely. Examples of nonimmigrant visas which permit dual intent include the H-1B and L-1A/L-1B visas. Visas which do not permit dual intent (and on which, therefore, an individual cannot begin a permanent residence process) include the B-1/B-2 visitors' visas, the F-1 student visa, the J-1 exchange visitor visa, and the TN Trade NAFTA visa for Canadian and Mexican citizens. Normally, a change of status to a visa which permits "Dual Intent" is required before a person on a nonimmigrant visa permitting only nonimmigrant intent can begin the process of applying for permanent residence.