Julia is a high-level, high-performance dynamic programming language for technical computing => http://julialang.org/

From the front page => Run Julia from the Browser. No setup.

This means that you can run the programming language from the browser without having to install Julia and the various dependencies onto your system. You can just run it from the your browser.

It is essentially Julia running in the browser, primarily as an IJulia notebook. Its a way to try Julia, and is good for teaching as students don't need to install anything to get started with technical computing.