Punishment can only be a fine. You cannot be placed in custody for violating an infraction. The most common examples of infractions would be traffic tickets such as speeding, driving without a license, failing to stop at a stop light, etc.
There are some situations that a misdemeanor or felony matter can be mitigated down to an infraction level as part of a resolution. Each case is different and your particular situation would have to be evaluated given the facts and legal issues present in your case.