IntelliJ IDEA Community Edition is the open source version of IntelliJ
IDEA, a premier IDE (Integrated Development Environment) for Java,
Groovy and other programming languages such as Scala or Clojure.

JetBrains leverages the open source effort on JetBrains.org to build
commercial products such as IntelliJ IDEA Ultimate, which includes many
Java EE, Web development and deployment-related features that are not
available in IntelliJ IDEA Community Edition. JetBrains also builds
different specific products such as RubyMine, WebStorm, PhpStorm,
PyCharm, AppCode and MPS, which serve the needs of different developer
communities. These products are also built on top of the open source
IntelliJ Platform.