Conclusion: Processing and Underwriting
After you apply for a mortgage and before you go to closing, the loan goes through the underwriting process. The lender will verify the information that you supplied about yourself and your finances, hire an appraiser, commission a title search, get title insurance, secure a flood certificate and get survey work done, if necessary.
If the underwriting process doesn't go your way -- in other words, if your loan application is denied -- you should find out what happened, get a second opinion and keep on shopping if the answer is still no.