Every month, the US State Department’s
Visa Office issues the priority dates for that month in its Visa Bulletin. It is issued for the different employment and family based categories. A priority date is the individual’s “place in line” for the visa, which means that the immigrant visas or the green cards will be available for the individuals whose priority date is earlier than the cutoff date.
If any individual’s priority date was “current” but later “move backwards” and become unavailable before the individual’s visa was granted, the individual has to wait unless it becomes current again.
In the start of the October 2015, the format of the Visa Bulletin has been changed, in that the latest column was also added which is also known as “Application Filing Date.” If the individual’s priority date is earlier than the Application Filing Date, they could file for the adjustment of the status and job authorization (on a condition that they are otherwise eligible and the USCIS point out on its website it would use the Application Filing Date for that month).
This can permit individuals to get the job authorization much quicker than before, where they had to stay for the priority date to be current (in the column of Visa Issuance Date) for both file for the adjustment and should be eligible for the green card.