Java is an object-oriented programming language created in 1995 by Sun Microsystems. It is widely used for both desktop and mobile applications as well as web applications. There are four main types of Java applications: standalone, web, enterprise, and mobile. Java can be used to create games, desktop programs, web applications, programs for robots, smartphones, and other devices. It has four main platforms: Java SE for core programming, Java EE for enterprise applications, Java ME for mobile applications, and JavaFX for rich internet applications. Basic knowledge of C/C++ is helpful to learn Java.