Quotes are intentions, not trades
A quote states what a participant is willing to do: a buyer posting a bid or a seller posting an ask. No transaction has yet occurred. This is the key difference from trade data, which records transactions that have executed. Quote data shows the current state of the market and how it is leaning, ahead of any trade.
The best bid, the best ask, and the top of the book
At any moment there are many bids and asks at different prices. The highest bid and the lowest ask are the best bid and best ask, which together form the top of the book: the narrowest available quote. Most basic quote feeds focus on this top-of-book view, as it determines the prices a typical order would meet first.
Why quotes change without trades
Quote data is often considerably more active than trade data. Participants continually add, revise, and cancel bids and asks as conditions change, so the quote can update many times between trades. Frequent quote changes without trades are normal and are precisely the activity that quote data, rather than trade data, is designed to capture.
Quote data and the order book
Top-of-book quote data shows only the best bid and ask. The full set of resting bids and asks at every price level is the order book. The difference between observing only the top of the book and observing its full depth corresponds to the distinction between Level 1 and Level 2 market data, though both originate from the same quotes posted by buyers and sellers.
Quote data on SiftingIO
SiftingIO delivers pricing under one schema across stocks, forex, crypto, and commodities, so quotes are represented consistently across markets. In markets distributed across many venues, the aggregated fair price reconciles quotes from several independent sources into one representative reference rather than the bid and ask of a single venue.