Bitsbox teaches kids to build simple apps by writing real, text-based computer code. The coding language we use is JavaScript, with the addition of a few dozen special commands (words, basically) that make it easier for newbies to build cool stuff quickly.
JavaScript is a very, very popular programming language which is used by millions of professional software programmers all over the world. Its main use is in programming web pages—just like the one you're reading now.
The apps that kids build with Bitsbox are actually individual web pages written in JavaScript. That's why they work on any computer or mobile device with a web browser. A web browser is the software you use to surf the web. Chrome, Internet Explorer, Firefox, and Safari are all common web browsers.