In forex, global variables are values stored within a trading platform, most commonly MetaTrader, that can be accessed across different charts, indicators, or expert advisors (EAs). Unlike local variables, which exist only within a specific program or session, global variables remain available for future use, even after the platform is closed and restarted. This makes them especially useful for strategies that require communication between different trading tools or timeframes.

For example, a trader might use a global variable to store the result of a signal generated on a higher timeframe chart, which can then be read by an EA operating on a lower timeframe. They can also be used to set conditions, such as marking whether a trade is currently active, or to store values like stop-loss levels, lot sizes, or risk limits.

Global variables in MetaTrader can be managed through the terminal or directly within code using specific functions. While they offer convenience and flexibility, traders should use them carefully, as incorrect handling may cause conflicting signals or execution errors. Overall, global variables act as a bridge that allows different parts of a trading system to “communicate,” making strategies more dynamic and coordinated.