f1签证是指什么时候？
F1签证 非移民签证，美国官方称谓是“nonimmigrant visa”简称为NIV。所有申请赴美留学生和访问学者的人士所申请的签证类型都是F1(学生)或J1(交换访问学者)。 F-1 Student Visa： For Students to take academic study， research or language instruction. J-1 Scholar/Exchange Visitor Visa： For Scholars and Exchange Visitors.
F－1 Nonimmigrant Student status is granted to those admitted by an accredited college， university， seminary， conservatory， institute of technology， trade school， business school or similar institution for a course of study in the United States. It does not apply to English Language students or other people who are enrolled only for English classes at schools which offer this as their primary purpose (such schools usually have ESL on the name too – i.e， English as a Second Language). If you attend such a school then your non-immigrant status will be classified as B1/B2. Note that some schools may advertise ‘English programs’ but if it includes full time studies they should not classify under this category. However， there could be exceptions depending upon what evidence you can present from your school about its program. A student cannot work more than twenty hours per week during term periods and must cease all employment when classes end for vacation periods; however， they can continue to work before and after regular class sessions， weekends， holidays etc， provided this does not interfere with attendance at their courses of education. This rule applies whether the person is a high school or postgraduate student， graduate student， post doctoral fellow or a teacher， professor or lecturer. There were changes introduced April 30th， 2008 where student can now work up to twenty nine hours per week while school is in session. The new rules came into force May 15， 2008 so any applications filed prior to these dates would be processed according to the old requirements. See our separate article called “Employment Issues Related to F1 Visa Holders”. After completing their education students need to obtain another type of visa， either H-1b for professionals or permanent residency through employment or family relatives who qualify via