Technical analysis uses statistical data from market activity, past prices and trading volumes to identify patterns and indicators that can predict a security's future performance. Hundreds of techniques exist, including chart patterns like bar charts, candlestick charts and point and figure charts that consolidate supply and demand forces into a visual representation. Technicians believe prices move in predictable trends and patterns until a change causes the trend to reverse, and chart analysis helps identify support and resistance price levels as well as common patterns like double tops/bottoms and head and shoulders formations that can signal trend reversals.