CA Gov't Code Section 84501

(a)

“Advertisement” means any general or public advertisement which is authorized and paid for by a person or committee for the purpose of supporting or opposing a candidate for elective office or a ballot measure or ballot measures.

(b)

“Advertisement” does not include a communication from an organization other than a political party to its members, a campaign button smaller than 10 inches in diameter, a bumper sticker smaller than 60 square inches, or other advertisement as determined by regulations of the commission.