The two most popular Scala IDE's are Eclipse and IntelliJ. There are a variety of other IDE's which support Scala, such as vim, Sublime, and emacs, but for the purposes of this guide we'll focus on these two.
By default, IntelliJ is set for Scala projects to be compiled externally. To compile through the IDE, you will need to point to the compiler when you create the project. Also, we recommend setting up your environment with one of our custom Scala themes.
When it comes to Eclipse, you have two options: download the core Eclipse IDE and configure extensions manually, or download Scala IDE for Eclipse. Scala IDE for Eclipse is the more convenient of the options, but the stable version often works with an earlier version of Eclipse.
Now you're ready to move on to Hello World and make your first Scala app!