The President can grant a pardon to a person who was convicted in a United States District Court, the Superior Court of the District of Columbia, or a military court-martial. 
Generally, a pardon is an expression of forgiveness. 
A pardon can help eliminate some of the consequences of a conviction.

Under Department of Justice rules, there is a five-year waiting period before a person can apply for a pardon. The waiting period begins when a person is released from confinement.  Or, if there was no prison sentence, the waiting period begins on the date of sentencing.