Technical indicators are mathematical calculations based on the price and volume of a security, used by traders to analyze market trends and make informed decisions. They help identify potential buy or sell signals by providing insights into market momentum, volatility, and overall market direction. Common types of technical indicators include moving averages, relative strength index (RSI), and Bollinger Bands. These tools can be applied to various financial markets, such as stocks, forex, and cryptocurrencies, assisting traders in predicting future price movements and optimizing their trading strategies.