Leading Indicators-These types of indicators signal future events. Think of how the amber traffic light indicates the coming of the red light. In the world of finance, leading indicators work the same way but are less accurate than the street light. Bond yields are thought to be a good leading indicator of the stock market because bond traders anticipate and speculate trends in the economy (even though they aren't always right).
Lagging Indicators-A lagging indicator is one that follows an event. Back to our traffic light example: the amber light is a lagging indicator for the green light because amber trails green. The importance of a lagging indicator is its ability to confirm that a pattern is occurring or about to occur. Unemployment is one of the most popular lagging indicators. If the unemployment rate is rising, it indicates that the economy has been doing poorly.
Coincident Indicators-these indicators occur at approximately the same time as the conditions they signify. In our traffic light example, the green light would be a coincidental indicator of the associated pedestrian walk signal. Rather than predicting future events, these types of indicators change at the same time as the economy or stock market. Personal income is a coincidental indicator for the economy: high personal income rates will coincide with a strong economy.