chat (n.)youdaoicibaDictYouDict[chat 词源字典]
1520s, "chatter, frivolous talk;" see chat (v.). Meaning "familiar conversation" is from 1570s. Chat show, for what in U.S. is a talk show, attested from 1969. Chat room in the online sense is attested by 1994, from the days when AOL ruled the Web.[chat etymology, chat origin, 英语词源]
talk (n.)youdaoicibaDictYouDict
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.