thanks greatly! this info is good!Residency programs give interviews up to 10 times the number of residents they want. So for example if they want 10 residents, they interview 100 candidates. Then after the interview they exclude for example 50 (do not rank them) and the other 50 they rank them from 1 to 50.
Then in the NRMP, their ranking will be matched with applicants' ranking.
For more information read Rank Order List.
How to increase the chance that they take you?
You should do well in the interview. like by showing them how interested you are in the specialty and in the program and in the city ...etc
Your professionalism, likability, communication skills, ...etc all play role in whether they'll rank you or not.
Your credentials (such as high USMLE scores) get you to the interview but the interview is about your personality and NOT ABOUT your credentials and medical knowledge.