The F-1 immigration status is granted to non-immigrants coming to the United States to pursue an academic or English language training program at a U.S. institution. F-1 students must maintain a full-time course load throughout their course of study at the school USCIS has authorized to attend.
For more information see Maintaining Legal F-1 Status
INS regulations divides temporary employment opportunities of F-1 students into several categories: Curricular Practical Training, Optional Practical Training, On Campus Employment and Economic Hardship Employment.
Curricular or Optional Practical Trainings are temporary employment opportunities related to the student's major area of study. Authorization from USCIS is needed before any practical training is granted.
Authorization to work part-time off-campus is only granted to students encountering economic hardship. Students need to meet conditions and receive authorization from USCIS before harship employment is granted.
What is the difference between F-1 visa and F-1 immigration status?
The VISA in your passport is a document required for entering the United States. It is issued at a US embassy or consulate abroad which shows the latest date on which you can apply to enter the country. The visa functions as a key to enter and it does not indicate how long you can stay in the country. While in the United States, you need not worry about your visa being expired. However when leaving and re-entering the US, you must have a valid visa stamped on your passport for your return.
The IMMIGRATION STATUS is the status granted to you at your port of entry once you are allowed admission in the United States. This immigration status is shown in your I-94 card and in most cases, your visa type and immigration status is the same. However, if you have applied for a change of status while in the US, you will be issued a new I-94 which reflects your current immigration status which may differ from the visa stamped on your passport. You do not need to apply for a new visa if you don't plan on leaving the US. If you leave, you must have with you upon re-entering the United States a valid visa on your passport that indicates your immigration status in the Unites States.