c. 1200, talken, probably a diminutive or frequentative form related to Middle English tale "story," and ultimately from the same source as tale (q.v.), with rare English formative -k (compare hark from hear, stalk from steal, smirk from smile) and replacing that word as a verb. East Frisian has talken "to talk, chatter, whisper." Related: Talked; talking.
To talk (something) up "discuss in order to promote" is from 1722. To talk shop is from 1854. To talk turkey is from 1824, supposedly from an elaborate joke about a swindled Indian.
Phrase talking head is by 1966 in the jargon of television production, "an in-tight closeup of a human head talking on television." In reference to a person who habitually appears on television in talking-head shots (usually a news anchor), by 1970. The phrase is used earlier, in reference to the well-known magic trick (such as Señor Wences's talking head-in-the-box "Pedro" on the "Ed Sullivan Show"), and to actual talking heads in mythology around the world (Orpheus, Bran).
late 15c., "speech, discourse, conversation," from talk (v.). Meaning "informal lecture or address" is from 1859. Meaning "a subject of gossip" is from 1620s (in talk of the town). Talk show first recorded 1965; talk radio is from 1985.