Negligence is a legal term which means a person or entity failed to use reasonable care which led to some other person being harmed.

You need four elements under California law in order to have a "negligence" against an at-fault party.  They are as follows:

1.  Duty owed by the at-fault party; the at-fault party owed a duty of due care to the injured party (like keeping floors free of debris so customers do not slip and fall, etc.);

2. Breach of that Duty; the at-fault party failed to keep the duty of due care;

3. Causation of Damages; the injured party, because of the breach by the at-fault party, was caused some harm (bodily injuries); see also proximate cause;

4. Actual Damages; the injured party suffered some harm (medical bills, and pain and suffering).
Remember, negligence is an "all or nothing rule" or "four part punch" means means you need all four elements above before you have legal negligence, and thus, a legal claim against an at-fault person or entity.