Are you applying to become a United States resident by marrying a US citizen or US resident? If yes, you will need to prove to the USCIS that you have a bona fide marriage. This means showing your marriage certificate or that you got married is not enough. You will need documentation to prove you have bona fide marriage.
A bona fide marriage means that you and your partner/spouse want to live together, build a future together and did not marry just for immigration purposes. This is very important because USCIS wants to make sure you are not trying to scam the system to gain US residency.
USCIS knows that many people can marry for convenience and get residency in the United States. So they need to be sure that your marriage is real, that you guys want to be together and did not marry just to get immigration benefits. This is why they need proof for the bona fide nature of the marriage.
When you file your I-130 petition package, this is the first stage to provide documentation which proves you have a bona fide marriage. This means you need to show them that you live together, have joint finances, have common friends, and spend life together.
So for documentation you can show that you have a joint bank account or have purchased a car or a property together. You can show that both of your driver licenses show the same living address or that you have a lease or mortgage with both of your names on it.
If you have kids together that really helps or if you are pregnant then you need to provide proof of pregnancy from your doctor. All these show that you both are building a life together and have a bona fide marriage.
