What does 'exclamation mark' mean in the operator?

Is means 'a variable is NOT EQUAL to something else (a variable or a value)'. 

Thanks Michael for helping Dongyup here.

Thank you for the comment.

Here is a (rather lame) example of this operator being used as part of a trigger. If the text entered does not equal 'Michael', then a layer with feedback is displayed.

Thanks Michael! 

Hi,

And Dongyup, if you'd like to see an example where it's used, here are some links to a demo I created for someone a while back. In this case, Learrners must type in the correct French words for neck, arm, and leg (if you want the answers: le cou, le bras, la jambe).

If they type them correctly, i.e., = = Equal to (ignore case), the answer is considered correct

if they type them incorrectly, i.e., != Not equal to (igore case), the answer is considered incorrect

The ignore case means we don't care if Learners use upper case (capital letters) or lower case.

Here'a Screenr describing how I made the demo

And you can access the Demo at this link:

http://refco27.com//Demos/Identify_Label_French_Words/story.html

Download sample

Finally, feel free to download the sample file

Thanks for sharing Becky! Very comprehensive answer as well!