Market Profile is a method of charting.
It is not extensively used outside of dealing rooms. I used to use this method quite a lot and found it to be very good in bond futures during volatile periods. I found little use for it in other markets, but that was just my experience.
Market Profile displays charts a little differently from other charts. Each period within a trading session, normally a 30 minute period, is assigned a letter. The trading range of that 30 minute period is then plotted again a vertical price axis.
The basic premise is that a market in equilibrium should show up in the shape of a bell curve. A market not in equilibrium will extend either up or down until it finds a balance of buyers and sellers and returns to equilibrium.
Below is a chart of three trading days in S&P futures. You can see the first and third days roughly show up as a bell curve. This is where buyers and sellers appear matched. The middle session shows a situation where the market was not in equilibrium and extended lower until it found support.
The best success I had with Market Profile was with the Japanese Government Bond (JGB). Combining Market Profile numbers with pivot point calculations would often give very accurate intra-day turning points. It was the same story with the Italian Government Bond.