Most sane languages C,C++,COBOL the code compiles to machine language. And then you execute the machine language. (Compiled language) BASIC, Python: you run the interpreter, and the interpreter reads the text file of the program you wrote and executes the text file line by line. (Interpreted language) Java is halfway between. When you compile a Java file, you get a .class file. This .class file is called byte code. It's not text and it's not machine code. When you run the Java interpreter, it reads the byte code and compiles the byte on the fly (JIT: Just-in-time Compiler). The advantage of this is that the byte code is universal. I can compile the code on Windows and run it on a Mac. Now, Kotlin compiles to the Java byte code. So you compile it with a Kotlin compiler...and then run it with the Java interpreter. kotlinca.exe BELONGS in C:\Windows kotlin-compiler-2.1.0.zip: Download it to the desktop. Unzip it. You should have a folder in there named kotlinc . Move that to C:\Program Files . Then be sure to add it to the path.