美国签证什么类型？
根据申请人前往美国的目的，可将美国签证分为访问（Visitor）、工作（Employment）、移民（Immigration）和非移民（Non-immigrant）四大类。 下面我们将分别介绍这四种签证的基本申请信息以及相应的签证类型和分类。
1. 非移民签证(Non Immigrant Visa) Non Immigrant Visa又叫做短期签证，是指申请人以短期的目的前往美国进行旅游或者商务活动而签发的一种签证，持有这种签证的人不能够在美国长期居住和生活；常见的非移民签证包括B1/B2旅行签证，F1学生类签证， M1商业移民签证等等，一般非移民签证的有效期限是1年或10年。对于大多数中国人来说，需要申请的签证大部分为B-1/B-2旅游（含探亲）签证。
2. 移民签证 (Immigrant Visas) Immigrant visas are for individuals who wish to live permanently in the U.S. and have a sponsor here， usually a family member of legal permanent resident or U.S. citizen. The category is commonly referred to as “Green Card” visa because it provides for lawful permanent residency. Most immigrant visas are issued at United States consulates abroad rather than embassies， with few exceptions. Immigrant visas cannot be applied for directly by people living outside of the US. They must do so through their sponsor residing inside the country either legally or illegally。目前，中国的移民签证主要分为三类：职业移民（EB类），亲属移民（F类）及特殊类别移民（IR类）。其中，职业移民与亲属移民的签证面签都是在美领馆办理，而特殊类别移民由于申请人少且多为海外美籍人士，因此由移民局在北京、上海和广州设立三个办事处负责受理材料并安排面试，不进行面签。
3. 学生类签证 (Student Visas) Student visas are non-immigrant visas that allow students to study full time in the United States on F， J， or M status visas. A student can be pursuing studies leading toward a degree or diploma from an accredited college， university， seminary， conservatory or other institution which is primarily engaged in educational activities; participating in research under an educator’s guidance; taking classes for self-enrichment or preparation for professional work; attending English language training; or engaging in short-term language training， exchange programs， or summer camps. Students may choose to stay temporarily while studying in America before returning home. However， if they plan to remain longer in order to find employment after graduation， they should apply for an H-1B Work Strictly For Professional Specialty Workers visa. In this case， the students will also need to obtain a work permit called a Social Security Number (SSN)， since they no longer qualify for the Federal Benefits Program and thus would not receive W-2 forms from employers nor pay federal taxes. There are two types