Java frameworks are pre-built collections of code that help developers create applications more efficiently. They provide a structured way to build software by offering reusable components, libraries, and tools. This allows developers to focus on the unique aspects of their applications rather than starting from scratch. Some popular Java frameworks include Spring, Hibernate, and JavaServer Faces (JSF). Each framework serves different purposes, such as simplifying web development, managing database interactions, or creating user interfaces. By using these frameworks, developers can save time and reduce errors, leading to more robust and maintainable applications.