How can an offense an offense be a crime and a tort?

Most acts which could produce criminal liability can also produce civil liability (making them torts).

This is because tort law and criminal law serve entirely different purposes: criminal law exists to punish wrongdoers for their acts, and focuses on a person's moral culpability.

Tort law, on the other hand, exists simply to compensate the victims of wrongdoing for their injuries.

So, suppose Al punches Bob in the face. Al has committed both a crime and a tort - in this case, they are both called "battery"

The state could bring criminal charges against Al for battery, and punish him with fines and jail time. However, the criminal court has no authority to compensate Bob for his injuries.

However, Bob could sue Al for the tort of battery. In such a case, if Bob won the lawsuit, Al would be required to compensate Bob for his injuries, by paying medical expenses, and possibly by paying for whatever pain, suffering, and emotional distress Al experienced.

As another example, suppose that somebody is murdered.

The murderer would by brought up on criminal charges by the state. Again, the purpose of this would be to punish him.

However, the family of the murder victim could also bring a lawsuit against the murderer for wrongful death, in which they could be compensated for the victim's lost wages, their pain and suffering, and the loss of the victim's companionship.