Many people have heard that by marrying a US citizen, a person can become eligible for a greencard.  While this does exist as a pathway to permanent resident status, for some it is not an easy path.  If you entered the United States without being inspected or admitted by an immigration official, you may not be eligible to apply for a greencard within the United States.  Instead you may be required to leave the US and obtain an immigrant visa from the US Embassy in your home country.  If you have been present in the US without lawful status for some time, leaving may trigger a bar to your reentry for either 3 years or 10 years.  This may be the case despite the fact that you have a US citizen spouse waiting for your return.  A Provisional Waiver grants relief from this bar in cases where the immigrant can show that the US citizen spouse will suffer extreme hardship if the immigrant is not allowed to return.  This waiver may be provisionally approved before the immigrant makes the decision to leave the United States for consular processing abroad, thereby shortening the time the family must spend apart.