From Traderpedia

Definition: Market Profile was developed by the CBOT and is a graphical organization of price and time information. Market Profile displays price on the vertical axis and time on the horizontal axis. Letters are used to symbolize time intervals.

Market Profile is an analytical decision support tool for traders — not a trading system.

Market Profile reveals pricing patterns from any market as they develop. By effectively organizing price and time information, it is possible for traders to see which price areas the market is accepting or which ones it is rejecting…and adjust their trading styles accordingly.

A price level that has been confirmed over time takes on added meaning. A price that is touched only briefly is just a price and little more. Confirmed by time, however, a price can reveal where the market places value.