The Java Standard Library is a collection of pre-written classes and interfaces that provide essential functionality for Java programming. It includes packages for tasks such as data manipulation, networking, and user interface design, making it easier for developers to build applications without starting from scratch. Key components of the library include the Java Collections Framework, which offers data structures like lists and maps, and the Java Input/Output (I/O) package, which handles file operations. By utilizing the Java Standard Library, programmers can save time and effort while ensuring their code is efficient and reliable.