Mobile Java refers to a set of technologies that enable the development of applications for mobile devices using the Java programming language. It provides a platform for creating software that can run on various mobile devices, ensuring compatibility and ease of use. The most notable framework within Mobile Java is Java ME (Micro Edition), which is designed specifically for resource-constrained devices. This framework allows developers to build applications that can function on a wide range of mobile phones and other handheld devices, making it a popular choice for mobile app development in the early 2000s.