Burden of proof
Whose job it is to prove a disputed fact. In a civil case the plaintiff must prove their claim by a preponderance of the evidence — more likely true than not.
Why it matters in a California small claims case
Small claims court is designed to be used without a lawyer, but it still runs on its own vocabulary, and a term you half-understand is a term that can cost you. "Burden of proof" comes up often enough in California small claims practice to be worth knowing precisely rather than approximately.
If you are mid-dispute and trying to work out what to do next, the short version of the whole process is this: ask in writing, file SC-100, serve the defendant and prove it with SC-104, bring documents to the hearing, and if you win, collect using the post-judgment forms. Individuals can claim under $12,500; entities under $6,250.
Not legal advice
This is a plain-language definition for orientation, not advice about your case. Terms can carry a narrower meaning in a specific statute than they do in general use.