Refusals can arise if you simply refuse to take a test that you are required to take. But you can also be charged with a refusal if you first say no, then agree to the test later. Or even if you are too drunk to be able to perform the test after you are asked to by the police.
What happens to me in court if I'm being charged with a refusal?
A refusal to comply will result in an "enhancement" or additional penalties, including the possibility of additional jail time.
A skilled attorney, however, can you use the facts to your advantage and possibly have the prosecution strike the refusal enhancement.
What does the DMV do when a refusal is alleged.
The DMV, after an adverse ruling at a DMV hearing (if you or your attorney requested one), can suspend your driver's license for a full year. This one year suspension does not include the chance to get a restricted license.