.4TH File Extension

Forth language's format is based on data stack and RPN (Revers Polish Notation). A simple example of its format:

12 10 * 40 + .
160 ok

This format equals to 12 multiplied by 10 plus 40, with "." printing the result of the mathematical equation to the user terminal.

NOTE: To create a 4TH file simply rename the extension of your plain text file that contains the Forth source code.