The Java Development Kit (JDK) is a software development environment used for developing Java applications. It includes essential tools such as the Java compiler, which converts Java code into bytecode, and the Java Runtime Environment (JRE), which allows the execution of Java programs. The JDK also provides libraries, documentation, and other resources needed for Java development. Developers use the JDK to create a wide range of applications, from mobile apps to large-scale enterprise systems. It is an integral part of the Java programming language, which was created by James Gosling and is widely used for its portability and performance across different platforms.