Market Profile Charts; the Pitt Traders Choice.
Market Profile Charts were developed in the 1980’s by Chicago Board Of Trade Pitt Trader J. Peter Stiedlmayer.
The letters on the chart show time units. 
“A” represents the first 30 minutes of trading, “B” represents the second 30 minutes of trading. The point of control is the area (price range) at which the most trades occur during the day.
The value area is the price range at which 70% of the action happens.
When the price is above and below the value areas this represents a possible ideal buying or selling point.
Positives
People who use market profile chart become evangelists to the cause. They believe it offers unique insights into buy and sell opportunities. It can be a good option if you are a quick-fire day trader.
Negatives
Can require quite an effort in order to learn how to use them, and very few stock chart services offer this type of charting.