Java Platform Standard Edition (J2SE) is a software platform that provides the essential tools needed by software developers to design, develop, and deploy applications and services in the Java programming language. It includes a runtime environment, libraries, and development tools such as compilers, debuggers, and JVM (Java Virtual Machine). J2SE is widely used for creating desktop applications, games, and enterprise solutions, and it offers a secure and portable environment for running Java applications on various operating systems and hardware architectures.