In layman's terms, oscillators are based on the principle that prices are likely to "consolidate" or "regroup" after a sustained run either up or down. Technical analysts use oscillators to describe the recent price activity of a commodity or security in mathematical terms, relative to a fixed range of possible values. Oscillators show an Overbought signal when a commodity has gone predominantly up for a period of time, indicating that the commodity is due for a pull-back. Oscillators show an Oversold signal when a commodity has gone predominantly down for a period of time, indicating that the commodity is due for a rebound. Examples of commonly used oscillators include the Relative Strength Index (RSI), Rate of Change (ROC) and Moving Average Convergence/Divergence (MACD).