Introduction to events
Events were introduced in LabVIEW™ 6.i. Before events, user interaction handling was largely dependent on polling controls inside a while loop, leading to inefficient and CPU-intensive designs. Event-driven programming enables your VI to react only when something important happens, such as a button click or value change, resulting in cleaner, more responsive UIs.
Events are handled with the Event Structure.

Figure 1. The Event Structure in the function palette