A simple Assault in California is an attempt to commit an act (battery) with the ability to carry it out. It does not require that a battery actually occurs.
There is also an assault with a deadly weapon where one uses a deadly weapon or instrument capable of causing great bodily injury and/or the victim is seriously injured. This crime is listed as a felony.
Battery is any unlawful and willful touching that is harmful or offensive. The crime of Battery becomes a serious felony when a "serious bodily injury" results in a significant injury. Examples include (but are not limited to a concussion, loss of consciousness, broken bones, and disfigurement).
Punishment in California consists of:
if you are convicted of simple battery pursuant to Penal Code 242 PC, you face all of the following:
informal (otherwise known as summary) probation for up to three years
up to six months in a county jail
a maximum $2,000 fine
possible community service and/or successful completion of a batterer's program
If you are convicted of aggravated battery with no "serious bodily injury", you will likely face a misdemeanor conviction, subjecting you to a maximum one-year county jail sentence.
However, If the person whom you battered suffers a serious bodily injury, you face a felony, punishable by:
2, 3, or 4 years in the California State Prison
a possible "strike" on your record