Java is a general-purpose, concurrent, object-oriented, class-based, and the runtime environment(JRE) which consists of JVM which is the cornerstone of the Java platform.
Java is among the most popular programming languages out there, mainly because of how versatile and compatible it is. Java can be used for a large number of things, including software development, mobile applications, and large systems development. As of 2019, 88% market share of all smartphones run on Android, the mobile operating system written in Java. Knowing Java opens a great deal of doors for you as a developer.