X++ is the object-oriented programming language used to customize and extend Microsoft Dynamics 365 Finance and Operations (F&O). It is built specifically for ERP development and combines SQL-like database operations with object-oriented programming concepts such as inheritance, polymorphism, encapsulation, and interfaces. X++ is used to develop: Business logic Forms Reports Batch jobs Services Workflow customizations Data entities Integrations One of the key advantages of X++ is its tight integration with the application metadata and SQL Server, allowing developers to perform database operations efficiently without writing complex SQL queries. Modern Dynamics 365 F&O development follows the Extension Model, where developers extend existing objects rather than modifying Microsoft's standard code. This approach ensures easier upgrades, better maintainability, and compatibility with Microsoft's One Version update strategy. X++ development is performed using Visual Studio, and code is packaged and deployed through Lifecycle Services (LCS) and Azure DevOps pipelines.