This is a little app. You type some text in the box at the bottom and this app displays it really big. It's for using your phone like a pen and paper, to tell people things when you can't speak with your voice.
The slider at the bottom controls the size of the text. Pull it left to make the text smaller. Pull it right to make the text bigger.
You can use it at http://richardbarrell.github.io/hey_emi/