banner (n.) Look up banner at Dictionary.com
c. 1200, "piece of cloth attached to the upper end of a pole or staff," from Old French baniere "flag, banner, standard" (12c., Modern French bannière), from Late Latin bandum "standard," borrowed from Frankish or another West Germanic source, from Proto-Germanic *bandwa- "identifying sign, banner, standard," also "company under a banner" (source also of Gothic bandwa "a sign"), from suffixed form of PIE root *bha- (1) "to shine."

Formerly the standard of a king, lord, or knight, behind which his followers marched to war and to which they rallied in battle. Figurative sense of "anything displayed as a profession of principles" is from early 14c. Of newspaper headlines that stream across the top of the page, from 1913.