Level 1
A trading service consisting of real-time bid/ask quotes for securities trading on the Nasdaq stock market and comparable information for securities quoted in the OTC Bulletin Board Service.
Investopedia Commentary
Basically, this just consists of real-time quotes. Also known as Level I.
Related Links
Electronic Trading Tutorial
See also: Bid/Ask Spread, Level II, Level III, Nasdaq
Also spelled: Level1, Level I, Level One