"Domestic Violence," in California, occurs whenever an assault and/or battery offense is committed against a current or former spouse, fiancé, or other romantic partner. The crime also includes the issuing of threats of inflicting bodily harm on such a person.
the punishments for domestic violence crimes are more severe than for "ordinary" assault and battery, the violation of trust and the taking advantage of the relationship with the other person as an occasion to inflict or attempt to inflict harm being seen as factors that make the crime more serious in nature. Additionally, child endangerment and child abuse are often charged as domestic violence offenses as well, and the sentences can be very severe since children are involved.
The exact punishment for domestic violence varies greatly based on the exact offense, but long jail or prison terms and heavy fines are common sentencing elements. And a restraining order that disallows the perpetrator to come within a specified distance of the victim or to contact him/her is also standard.
Domestic violence is an extremely common offense in California, but it is also common to be falsely accused of this crime out of a spirit of revenge. Other times, the "victim" may actually be the true perpetrator. And still other times, the defendant had not intent of threatening/harming the victim (it was an accident or a misunderstanding). A good defense lawyer will be able to get many domestic violence charges dismissed or at least reduced.