Consular processing is the way of obtaining US legal resident status after an interview at a US embassy abroad.
Consular processing is the appropriate procedure if the immigrant is not in the United States, but would like to immediately move forward with a legal resident application and does not have a “dual intent” visa (most do not). It is also a good option if the family is residing abroad and not yet ready to move to the United States.
Consular processing may be the only option available if the immigrant is not in the United States and unlikely to be granted admission to the United States either because they cannot obtain a visa or because they might be denied entry to the United States even with a visa (see discussion regarding immigrant intent in the “adjustment of status” section).
The downside of consular processing is that it can take a long time from start to finish, and if the family is separated during this time, consular processing can be a significant hardship.
During the time that the case is pending, it is likely that the immigrant will not be issued a visa to travel to the United States (unless the visa type is “dual intent” which is rare). If the immigrant already possesses a visa, or is otherwise eligible for entry to the United States under the Visa Waiver Program (ESTA), it is generally likely, but not guaranteed, that the immigrant will be able to travel to the United States while the case is pending.