Java was originally developed by James Gosling at Sun Microsystems in 1995. It is a platform independent, object-oriented programming language that is both interpreted and compiled. Java applications are compiled to bytecode that can run on any Java Virtual Machine, making Java portable across various operating systems. Key features of Java include being simple, secure, portable, object-oriented, multithreaded, and having high performance. Common applications of Java include mobile applications, web applications, and enterprise applications.