How to force quit an app or program on Mac

[iMore.com]

Chances are you?ve probably encountered the ?rainbow wheel of death? once or twice during your time as a Mac user. Instead of sitting there getting more frustrated with each passing minute, let us show you how to find the program causing the problem and force quit the app.

Full story from the iMore Blog...

 

[robertk328]

Doesn't happen often, but I do need this periodically. I usually just hold the alt/option key and click the dock icon, which will show the Force Quit option.