(Originally posted on Doug's MATLAB Video Tutorials blog.)

There are three inputs to every automatically generated callback from GUIDE:

function edit1_Callback(hObject, eventdata, handles)

A common question that I am asked is "What is the handles structure?" This four minute video will show a simple GUI where you edit some text, and press a button that will copy that text into a third uicontrol. This is all done using the handles structure. The other two inputs: hObject and eventdata will be briefly discussed also.