Developing Expert Advisors in MetaTrader 5 relies on an event-driven architecture where the trading platform triggers specific predefined methods based on market activity. Rather than running continuously, these programs respond to particular occurrences such as price fluctuations, the passage of time, or trade executions. Core functions like OnInit() and OnTick() manage the lifecycle and primary logic of a strategy, while additional tools handle order placement, indicator data, and risk management. While the MQL5 language offers vast functionality, professional development typically focuses on a small subset of essential commands to ensure system stability. Understanding these automated hooks transforms the coding process from unpredictable guesswork into a disciplined form of financial engineering.