IntelliJ
In plain terms
A powerful Java IDE from JetBrains.
Going deeper
IntelliJ IDEA offers deep code intelligence, refactoring, and tooling for Java and JVM languages, beloved for its productivity features. It's a premium developer environment.
Under the hood
Smart completion, refactoring, and analysis; the basis for Android Studio and other JetBrains IDEs.
Examples
Java/Kotlin development, refactoring, Android Studio, Spring, enterprise.
Think of it like...
Like a master craftsman's fully-equipped workbench tuned for Java.