The pre-approval stage of getting a mortgage typically relatively pain free. First, a loan officer will ask you some questions and get basic verification of your income & credit score.
After you've found a home, made an offer that both parties have agreed to, you can move to the next step in applying for a mortgage.
The underwriting process is where the lender seeks to understand you and the property as a borrower and get comfortable giving you a loan.
Once the loan is underwritten and the lender has gone through their checklist of requirements for the loan to their satisfaction, they issue a loan commitment.
At closing, there will be a giant stack of documents to sign. The most notable documents will be the note and the mortgage.