An EAR (Enterprise Archive) file is a deployment unit used in Java EE (Enterprise Edition) environments. It's essentially a JAR (Java Archive) file with a specific structure and purpose. EAR files are used to package and deploy complete Java EE applications to application servers like GlassFish, JBoss/WildFly, WebSphere, and WebLogic. The EAR file contains all the necessary components for the application, including EJB (Enterprise JavaBeans) modules, web modules (WAR files), resource adapter archives (RAR files), and any required libraries or dependencies. The EAR file also includes a deployment descriptor (application.xml) that specifies how the application should be deployed and configured on the application server. This descriptor defines things like security roles, resource references, and other application-level settings. Using EAR files simplifies the deployment process by packaging everything into a single, self-contained unit, making it easier to manage and distribute Java EE applications. The application server uses the information in the EAR file to properly configure and deploy the application, ensuring that all components are correctly initialized and integrated.