Mathematical calculations plotted and tracked on a price chart that can help traders identify signals and trends within the market. There are 4 main types of indicators: trend (eg MACD), momentum (eg RSI), volatility, and volume. Many other types of indicators have arisen as different trading styles have become more defined and nuanced.
We don't know everything about the markets. We're just devoted to learners. Taken from those smarter than ourselves, here's how we define Trading Indicators.