Java is a simple, object oriented, concurrent and general purpose programming language. Some other important features of java are robust, secure, portable, interactive and high performance. Java was developed by Sun Microsystems in 1995 since then it has become very popular due to its feature like platform independent and robust in the case of memory management.
Because java has its own run time environment (JRE) and API so it is called platform.
According to Sun Microsystems, nearly 3 billion devices run java. Some of these devices are mobile phones, games, robotics, application in banking sector etc.