An immigration lawyer is an individual who concentrates on immigration law and distinguishes all the requirements and settings to arrive at another country as a legal, permanent resident.
It is completely possible to experience the whole visa process without signing an immigration attorney. They're not officially required to be part of the process. But US immigration law can be problematic and confusing for somebody to try to understand on their own. An immigration lawyer will distinguish the ins and outs of US immigration law and will validate you don't make mistakes that could postpone or prevent your application from being acknowledged. An Immigration Advocate can also prevent you from making expensive mistakes.
Individuals who will most benefit from the facilities of an immigration attorney are those who have not gone through the system earlier or know no one who has. There are people who have effectively made their way through the system without an immigration lawyer, but those people habitually also have a strong support group (friends or relatives) who have been over the process.
If you don't know where to catch an immigration attorney, there are immigration resource hubs and communities that can help you with this. There is a policy to put on for an immigrant visa to upsurge your chances of having the visa approved.