Patterns are repetitive configurations of bars/candles that sometimes accompany changes in trend. Using patterns may give you an idea of future development of the trend. Three types of patterns are available in thinkorswim: candlestick patterns, classical patterns, and Fibonacci patterns. 

Candlestick patterns consist of several candles, while classic patterns are vast formations that take at least several weeks to develop. Configurations of candles in Fibonacci patterns are based on Fibonacci ratios. 

The library of the available pre-defined patterns of all types can be found in the Reference section.