An oscillator is a technical analysis tool used in financial markets to identify potential overbought or oversold conditions of an asset, helping traders gauge momentum and trend strength. Oscillators fluctuate between a defined range, typically displaying values from 0 to 100 or -100 to +100, and include popular indicators like the Relative Strength Index (RSI), Stochastic Oscillator, and Moving Average Convergence Divergence (MACD). By analyzing these indicators, traders can make informed decisions about entry and exit points, as well as potential market reversals.