Java is a general purpose, object oriented, class based, high-level programming language with a syntax similar to C++, but fewer low-level features. Java programs are normally compiled into byte code that can run on a Java Virtual Machine which is part of the Java runtime.

Jakarta EE

Jakarta EE has developed a comprehensive set of open specifications that are used to develop modern, Java application servers. With Jakarta EE, Java developers are assured that they can develop solutions that can be deployed to a wide range of application servers, in the cloud or on premises.

Jakarta EE brings a lot of value to the ecosystems that support the Java programming language, and other languages that targets the Java Virtual Machine, such as Kotlin. Targeting Jakarta EE allows Java developers to focus on the particular needs of their solution, based on standards compliant services, such as:

Jakarta Annotations
Jakarta Authentication
Jakarta Debugging Support for Other Languages
Jakarta Servlet
Jakarta Server Pages
Jakarta Expression Language
Jakarta WebSocket
Jakarta Web Profile specifications
Jakarta Activation
Jakarta Bean Validation
Jakarta Contexts and Dependency Injection
Jakarta Dependency Injection
Jakarta Enterprise Beans
Jakarta Faces
Jakarta Interceptors
Jakarta JSON Binding
Jakarta JSON Processing
Jakarta Mail
Jakarta Managed Beans
Jakarta Persistence
Jakarta RESTful Web Services
Jakarta Security
Jakarta Standard Tag Library
Jakarta Transactions
Jakarta XML Binding
Jakarta Authorization
Jakarta Batch
Jakarta Concurrency
Jakarta Connectors
Jakarta Enterprise Web Services
Jakarta Messaging
Jakarta SOAP with Attachments
Jakarta Web Services Metadata
Jakarta XML Web Services

There are many popular Jakarta EE based application servers, among them:

Apache TomEE is a Jakarta EE 9.1 certified application server that extends Apache Tomcat.
Oracle WebLogic Server.
IBM WebSphere Application Server.