Top of Book (Best Bid
/Offer) market data contains all top bid, bid size, top ask, ask size, last trade, trade volume, and timestamp data for exchange traded products.
Source (with edits): http://www.cmegroup.com/confluence/d...+of+Book+-+BBO
Top of Book data forms part of the Order Book, other parts of the Order Book include Depth of Market
(or Level 2
Also abbreviated as ToB and BBO.
Also know as Level 1 data.